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PWM control for some medium/high powered Delta fans, worth it over undervolting?

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Max0r

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For ages I've been used to controlling these 12-20watt mid 100's max CFM Delta fans the usual way, through voltage adjustment devices, so I can run these powerful 120x38mm fans at low voltage, enjoying both superior turbulence against fins and the moderate noise levels (some might call very high) I demand, compared to the quiet 25mm fans everyone uses.

Well, it seems PWM is the thing now, and for good reason. It would appear it is both more power efficient for any given level of fan performance... AND generates less heat in and of itself compared to the under-volting method. I see also that there are many PWM Delta fans on the market now. The only problem, of course, is that the fans I prefer running at partial speed draw enough power that I wouldn't want to attach them to the motherboard headers. I've found a bunch of PWM fan hubs that use SATA/molex power from the PSU, and are controlled entirely by one input from the motherboard. This is good enough for me, however, they do not really specify what their max power per channel or total is. I'm not sure these things could handle, say, 5 of these fans.

Some questions:

1. Just how superior is PWM in terms of power efficiency compared to the usual undervoltage method?
2. Is it true that the undervoltage method really does put out a bunch of extra heat compared to PWM?
3. Are there any PWM fan controller products out there with actual physical control knobs for each individual fan, like the oldschool 3.5/5.25 bay voltage controllers? I can't seem to find any.
 

EarthDog

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1. I've never known it to be.*
2. See #1
3. Lamptron makes some awesome fan controllers. That's all I can think of with knobs off the top of my head.

* When I was reading your post, I was actually wondering where you heard that from. It may darn well be true, but, in all my years, I never knew/heard of those things (efficiency/extra heat from undervolting). Perhaps someone can shed some light on that, or bunk it.
 
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Max0r

Max0r

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TBH I hope this efficiency/heat difference between PWM/undervoltage really isn't a thing, or even with high power fans, would be so small that it's insignificant. Because... those Lamptrons you mentioned are looking really good right now, and the closest thing I could find in PWM land is those tiny little Noctuas with the tiny knob that would basically be part of the wire management. Aside from those, it seems literally every other PWM control/hub product either takes its control from motherboard headers, or even worse... PROPRIETARY SOFTWARE :bang head:sick:

I definitely don't care about ultra precise control, or being able to run at ultra low sub 40% power. So in that respect, PWM means nothing to me. However, I just confirmed my little new case can easily fit 38mm thick fans in the front with the panel on without it even getting close to touching them, which means aside from the HDD cage, I can slap 5 of these babies in pushpull on the front radiator. I figure if I run them around the equivalent of 7 volts, they'd be wanting a total of 30-45 watts depending on which model/s I end up using. To be fair, under low load situations, I may want to try to run them even slower, as this would generate less heat in my oven of a room, so PWM could take the cake in that respect. However, I would need motherboard control to do this efficiently, given that there aren't any easy to use manual control products for PWM as far as I can tell. Nonetheless, the total wattage demand at ~half power isn't that high, so unless PWM can boast very large percentage gains in efficiency, it may not be worth the trouble.
 
Joined
Dec 13, 2005
Yeah, more precision in fan control is the only advantage I know of with pwm.

That being said, there are motherboards that can handle one, maybe two of them on a header. Just checked the specs on mine, they're rated for 12v/2a each. Just throwing it out there if you do decide on that lower level fine control.
 

EarthDog

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To be fair, under low load situations, I may want to try to run them even slower, as this would generate less heat in my oven of a room, so PWM could take the cake in that respect.
Ehh, if your PC is 'outputting' 150W of heat, it's going to do so, regardless of your fans.

That said, set them all on low, period. It's not like you need more. You could even get away with much quieter and less power-hungry fans. ;)
 
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Max0r

Max0r

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One bit of good news. It's possible my total fan power requirements may end up being on the low end of my estimate, or lower. This guy in this video is running 5 of basically the highest power fans I would consider, each of which is specified as 1.6a. They sound loud as hell in this video and I'm thinking they're higher power than the two different 120x38mm high speed Delta models I've been using all these years.


Those 5 fans at full speed are only pulling about 65 watts out of the wall, so 13w each. In contrast, my old 120x38mm high speed Delta triblade that I just tested now is only specified as 1.2a, and I'm finding that it only pulls about 9-10 watts out of the wall at full speed. However, when it starts, it seems to spike to AT LEAST 22 watts.

So this is good because it means that even if the PWM route is more efficient, the difference is likely even more insignificant.

The bad news is that indeed, although one of the mobo headers is 3a/36w and one is 2a/24w, given how heavy that fan can spike up from a stop, it would only be safe (and maybe not even) for the motherboard to run 1 of these fans on the biggest baddest header. I wouldn't want to risk over-spiking on the 2a one. And the rest of the sysfan headers are only 1a/12w. To hell with that! Nonetheless, PWM control from 1 or more of these headers can still be routed to those fans via one of those hub products... but those things seem really dodgy to me.

The guy who made that video apparently did some nutball PWM stuff with 12 or more of those Delta fans. I'm still scouring his very long threads to see if I can find some insight.

Ehh, if your PC is 'outputting' 150W of heat, it's going to do so, regardless of your fans.

That said, set them all on low, period. It's not like you need more. You could even get away with much quieter and less power-hungry fans. ;)

Yea. They sound amazing on 7v. Not too loud, not too soft. Very soothing. And at 7v they push through things waaaay better that way than quiet fans do at full speed. Maybe they'd sound even better even lower, given that 5 of them might increase the noise output and need further attenuation. For that, PWM would offer an advantage. I've already managed to get one core to peak at 96 with the stock fans, in a room that's much cooler/dryer than it will be during the warm season. But that was with prime95 pushing 230 watts, far beyond the wattage other CPU stress tests push. However, even only pushing 120-150 watts, if the room heats up to 82 degrees, gets super humid, and there's some dust buildup in the case, I'll be damn happy to know I'm pushing those temps at least several degrees lower than they otherwise would have been, especially considering higher heat in the AIO loop means faster evaporation over time.

But even if that wasn't a potential issue, come on. How can anyone not use these fans? Silent PCs are death!
 
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Max0r

Max0r

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I dunno man this is throwing another curveball at me. I can't believe I'm so ignorant on this topic (actually I can believe it)

2022-02-17_182438.png

So does this mean the superior DC fan control option is a rheostat based controller instead of a linear voltage regulator, from a heat standpoint? :shrug:
 
Joined
Dec 13, 2005
Linear regulators generally are pretty inefficient yeah, it's why a lot of electrical designs needing a regulator (in general, unsure of fan controllers) moved over to switching regulators. The last time I used a rheostat as a fan controller, actually used it to drive a 20w Delta on a GPU cooler, it got warm but never hot. So yeah they're more efficient.

But honestly, you seem to be stressing over it. Let's go back to your OP. You seem to be stressing over efficiency. If you do go a more energy efficient route, what do you hope to achieve? Lower power use, lower heat?
 
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Max0r

Max0r

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Linear regulators generally are pretty inefficient yeah, it's why a lot of electrical designs needing a regulator (in general, unsure of fan controllers) moved over to switching regulators. The last time I used a rheostat as a fan controller, actually used it to drive a 20w Delta on a GPU cooler, it got warm but never hot. So yeah they're more efficient.

But honestly, you seem to be stressing over it. Let's go back to your OP. You seem to be stressing over efficiency. If you do go a more energy efficient route, what do you hope to achieve? Lower power use, lower heat?
These are my objectives:

1. I absolutely must hear my primary system running a undervolted medium-high powered Delta 120x38mm fans. I cannot live without that sound in my computing. As an added bonus, if I'm running 5 of them I just might achieve eargasm. However, to fully optimize my eargasm, the ability to lower them down a bit more with PWM MAY BE A CONSIDERATION.
2. I want to overprovision my cooling on the i7 Alder Lake so I have an extra security buffer to avoid roasting my AIO loop. The stock fans are hardly doing anything (taking off the breathable front panel + filter lowered peak core temp by 4-5 degrees in prime95 tests, which is good when your peak temp is 96 degrees). These fans are so weak you can't even feel anything at maximum except around the sides! An undervolted Delta as I described will utterly destroy these in performance, and sound great in the process. 5 in pushpull on a 360 radiator? Yes please.
3. Without going into my life story I just need to stress that my room that I operate this system in gets very hot and humid during warm weather, and my room is a god damn dust pit, hence #2. As such, I'm paying some extra attention to some details which might allow me to knock off some heat watts while maintaining high performance. I'm even considering undervolting the CPU if I don't have to sacrifice any serious power to do so, but only if that doesn't prevent it from dynamically parking/slowing cores that aren't needed. My usage may be heavy, but it will also be very spikey and dynamic, so I need its automatic ramping up/down to also be in effect. I've already chosen a titanium PSU because if I can knock off a few watts here, 15 watts there, maybe even 20 watts there, that's less heat. Sometimes it just takes one straw to break the camel's back in this room in the summer. It's a constant war to cool it without having to keep my door/window open all the time (10 hours of lawn mowers/leaf blowers/room mates? No thanks).

Due to a serious CPU bottleneck I had to do a major upgrade to a lot more cores with much greater single thread performance as well. I'm glad I did, even just starting to use this system, it absolutely smokes my 7700k in so many ways. But with great power comes great heat :) So I must find a way to at least shave some of it off before the summer hits and its time for me focus entirely on my work.

So yeah, if I think I can somehow shave off maybe 15-20 watts by being able to run these fans even slower (assuming the sound/airflow is still good with that), or just by using a controlling mechanism that is more efficient, then I think it's worth it. And even if this entire project turns out to be a waste of time, at least I'll learn something for later. After all, at the end of the day, I'm more than just a user. I sometimes am even a hobbyist. I don't mind a little extra stress when I'm doing a build every several years. It means extra enjoyment and smooth sailing in the years to come. :thup:

Bee tee dubz, if that's a little off the deep end I totally understand. I never said I was mentally all there. Participate at your own risk. :bday:
 

Voodoo Rufus

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Sep 20, 2001
There's a guy on Youtube who made a modern PWM controller specifically for high power fans like Deltas and Sanyo Denkis. I made one twenty years ago but not a very good one. I would like to run thicker 38mm or 50mm fans on my radiators, and am thinking of picking up a 3D printer so I can make my own large format fan shrouds to space the fans from my radiators. I sold my FFB1212VHE fans years ago, but they were great throttled down.

I still have a op-amp based Sunbeam controller. Linear controllers like that will dissipate more heat compared to a highly efficient PWM controller, but if you can sink the heat, who really cares?

The highest power PWM fan headers can take 1.5-2A. Most can only take 1A.

Noctua makes a PWM controller with a knob that can take SATA auxiliary power. https://noctua.at/en/na-fc1

I want to read more on this thread, but it's late. I'll revisit it later as I think I can give more feedback.
 

MaddMutt

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Jan 12, 2015
I LOVE My high speed Delta's for my 360mm rads. I have both the 1.60a & 3.24a versions and run them all through a 2x Lamtron FC2 45w 6ch controller. When I don't need the cooling, I turn them down/off. I would look for a fan controller as this is better than just a fan header. I'm not sure of your MB BUT many are listed as 12v/1a max ( I have older MB's) for the CPU header.
 
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Max0r

Max0r

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I was seduced by the Lamptron FC5 V3 and ordered one, along with 3 different Delta fans and some other assorted fan related goodies at Performance-PCs. Two of the Deltas I ordered are identical except for 1 thing: One is a conventional 3-pin style, the other is PWM 4-pin style. They are the same base model otherwise: AFB1212HHE, 0.7a. I also got an AFB1212SHE 1.6a which is also a conventional 3-pin.

1. One thing I have to say is, the Lamptron is absolutely amazing. It looks great, functions great, the temperature probes are showing consistent temps.

2. Second bit of good news is that the conventional 3-pin HHE 0.7a has that same wonderful Delta electric buzzing motor sound I've come to know and love from the Delta I have on my previously primary system.

3. At higher speeds, these fans sound much worse than my old Delta triblade 120x38. The AFB1212HHE's max out around 2900 RPM or so. At the same RPM around 9.5 volts, the triblade has a much lower pitch loud hum. The AFB1212HHE's on the other hand, have a higher pitch sound to them. It's like a less intense, lower pitch version of the screamer whine of the super high speeds. However, in push, I seem to be feeling more air at the other side of the radiator than with the triblade. It's not a big difference, but enough to be noticeable if I'm specifically feeling for that. So they seem to push past resistance better, generating more turbulence.

4. I cannot for the life of me get the PWM fan to show RPM or function in PWM form. In DC mode, neither on the Lamptron nor on the motherboard does it display RPM. In DC mode on the motherboard, or connected to the Lamptron, its speed will be controlled just the same as the 3-pin fan (the motor sounds quite a bit different at lower RPMs, and the PWM fan has a weird starting noise, while lacking the signature motor buzz, but they sound about the same toward highest RPMs). If I switch the PWM fan to PWM mode on the motherboard, it only runs at max, and refuses to be slowed down, again not showing RPM. I noticed on the connector that the 3rd pin was a yellow wire, and the 4th blue. I thought the tachometer wire would be blue, and the PWM wire yellow. They're lined up the same coming from the motor. I'm considering popping them out of the 4 pin connector plastic housing and swapping them around to see if that fixes things.

Interestingly, on the Delta website itself, it indicates the Blue as being tach, and the Yellow as being PWM control:
2022-02-24_051133.png

I'm really thinking swapping them at the connector molding may be the thing to do. What do you think?

5. From a strictly sound perspective, I'm already finding PWM to be highly inferior in terms of the motor noise. BUT, I have not yet tested what it sounds like if properly functioning at low speed with PWM control. Maybe that will change things.

6. The 0.7a medium/high speed fans seem to be more than enough power for me. At 5-6 volts I'm thinking they'd be too quiet. Anywhere near max speed, too loud. This might be the perfect balance actually, giving flexibility in both directions from the sweetspot. It's also nice to know my fan power requirements will be very limited, further negating the importance of potential increased efficiency from PWM. I'm not sure what the Lamptron's control mechanism is exactly, but I'm hoping it's not one of the highly inefficient types. As long as that's the case, I doubt PWM would help much in my situation to minimize wattage being drawn into my room.

7. I have yet to test the 1.6a fan. I'm wondering if I'll be able to run it slow enough ^_^
 
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Max0r

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Tested the 1.6a SHE - Only 3 seconds in and it already ripped a hole in my shirt >_< Good thing it was already starting to spin down, or things could have been much, much worse :rofl: After regaining my wits, I found that at maximum, it's only pulling around 9.5 watts out of the wall, but it is much louder than the HHE 0.6a fans at maximum, and pushes a lot more air. I tend to wonder if it would pull more out of the wall if it wasn't behind a fan controller. Doesn't matter to me anyway, because I doubt I'll ever be running it at maximum. That being said, the way it sounds is quite interesting. It has a similar motor buzz to the HHE. At low speeds, it doesn't sound as good as the HHE. However, at higher speeds, the SHE begins to sound better. At comparable RPM, as the HHE starts pushing, say for example, 2100 RPM, the SHE at this RPM actually sounds a bit softer and has a more pleasant note to it. As the RPMs increase, the lower power HHE has a much harder and higher pitch edge to the sound, while the SHE sounds more chill. It's like the SHE is just not working as hard to produce the same RPMs, giving it a more soothing sound. However, once you push the voltage high enough on the SHE, it does eventually get quite a bit louder and more high pitched, but what else would you expect when pushing it at or near its maximum? However, at very low speeds, the HHE sounds better.

Lamptron Efficiency - I am impressed with the Lamptron controller's efficiency. When plugged in with all the knobs set to zero (and 6 temp probes plugged in), just powering the probes/display, it seems to be pulling about 1 watt from the wall. If you set a knob to maximum, without anything plugged into it, it seems to bleed around 0.2 to 0.3 watts. The only reason I'd do something like that is my 120 triblade goes to the big molex and has a separate 3 pin connector with just the tach wire, which I have to plug into another channel and set its knob to 12v for the RPM display to function right. So that costs an extra 0.25 watts or so. I think it's worth it. When powering a fan on a Lamptron controller channel, the power draw from the wall seems to track very well with the fan's voltage setting. It appears if any power is being wasted, it's ridiculously small. At low speed settings, these fans, individually, are pulling 2-3 watts. Medium speed, maybe 3-4 maximum. The power usage curve seems to stay very low until you get near maximum power and then it rises very fast, along with the fan's noise.


Sound Conclusion - From the fans tested, I'm not 100% sure whether I'd prefer the sound of the low power HHE's or the higher power SHE's. It depends entirely on what my sweet spot RPM is going to end up being for sound. If it's lower, the HHE's will win, as their low RPM motor sound is just perfect. If it's higher, the SHE's will win, as their sound is much less harsh at comparable RPMs to the HHE's once they're pushing higher RPMs. More testing will be required. If possible, however, I'd also like to maybe find some different Delta or even other brand models to test. Maybe I can find an even better sound. I also have yet to test things fully in the difference in sound in pull on these fans, or whether there is a significant difference with the case front panel on. This may point things in one direction or another.


PWM vs Undervolting Conclusion - At this point I'm convinced I have no reason to give a damn about PWM unless I wanted automatic fan control based on temperatures in which I wanted to save an extra watt or so per fan when running at minimum, but that would mean my PC would be too quiet, therefore I'd never want that. A few watts savings at most would make no real difference I think, for my room's heat levels. Additionally, I wouldn't want to run things as slow as possible anyway, because extra cooling for the AIO loop means a longer life for it, with less evaporation. Of course, that could also justify running fans much faster, but I'd rather seek a good middle ground of perfect sound, higher than usual cooling performance, and low power draw.

That being said, I can't hammer the last nail in this coffin until I actually get PWM working on the PWM fan and put it through its paces.
 

EarthDog

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lol, too quiet... good one!!!

I really think you're swimming in the minutua with worrying about AIO temps and a longer life. These things will easily go past their warranty if you set the fans to low and allow for a few more degrees. For years now, my loops and AIOs have been set to low and easily lived past their warranted lifespans. In fact, I retired my decade old custom loop and went with an AIO. All my kids systems have/had AIOs set to low and they all are still currently living well past their warranty period too.
 
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Max0r

Max0r

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Well, I'm new to this whole AIO thing. Never did water cooling either. I don't mind getting mucked up in details on the front end. It means being less mucked up on the back end. For what it's worth, I'm definitely not planning on increasing fan speed just to try to extract more AIO lifespan. If anything, I think my preferred Delta fan sound levels from a strictly ear-pleasing perspective will more than do that compared to the stock fans, and anything past that will likely have too much diminishing returns to care about (and even what I'm doing may have too much diminishing returns to care about, but when you factor in dust buildup and extreme room heat levels, it actually might be less diminishing returns than it would first appear).

I can't be the ONLY one who hates quiet computing... can I? Can I?!?!?! :shrug:
 
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Max0r

Max0r

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I figured out the problem with the PWM fan. Indeed the wires were reversed. With the blue being pin 3 and the yellow being pin 4, it correctly displays RPM and is in fact being controlled with PWM on the motherboard. This will introduce more sound/power testing which I will do later. I still find it odd that Delta would wire them from the motor in a different order than they should be at the connector. I almost wonder if maybe they're not the ones who do the wiring, and they just sell huge quantities of unwired fans to different parties that do.
 
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Max0r

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After doing some very tedious testing (if I didn't control the CPU temp, baseline fans off draw would increase with CPU temp increase) involving constantly switching back and forth between zero fan draw and each test (while maxing out the lamptron fan between tests/baselines to keep the CPU temp bottomed out and baseline power draw stable)...

What follows is a large amount of stuff that turns out to be a relatively small difference in my situation. But, I'm satisfied that I've done the testing to settle this subject/decision in my mind, and now I have a big frame of reference for future cooling/fan operations.

TLDR: PWM is more efficient, but not enough to make a difference for me. Only read on if you like nerding out over details.

This is not the most precise testing because I think the Lamptron in particular just rounds the RPM in large chunks like 60, but whatever. It's close enough soundwise etc. I tried to match up the RPMs as close as I could.

There are 5 tests I did for each RPM. 2 tests for the HHE 3-pin fan, 3 tests for the HHE PWM fan.

Key:
HHE LAMPTRON = 3-pin fan on Lamptron controller
HHE MOBO = 3-pin fan on mobo header controlled with DC mode
HHE PWM MOBO DC MODE = 4-pin PWM fan on mobo header controlled with DC mode
HHE PWM LAMPTRON = 4-pin PWM fan on Lamptron controller
HHE
PWM MOBO PWM = 4-pin PWM fan on mobo header controlled by PWM

Motherboard PWM mode adds about 0.25w at all times even at 0 RPM, compared to DC mode & no control (which just runs at 12v)

-[ ~1740 RPM ]-
Max's Version of "Quiet" Potential "Low Noise" Sweetspot
HHE LAMPTRON: 2.4w
HHE MOBO: 3.6w
HHE PWM MOBO DC MODE: 2.95w
HHE PWM LAMPTRON: 1.9w
HHE
PWM MOBO PWM: 1.6w + 0.25w = 1.85w


-[ ~2000 RPM ]-
Potential Sound Sweetspot
HHE LAMPTRON: 3.3w
HHE MOBO: 4.4w
HHE PWM MOBO DC MODE: 3.35w
HHE PWM LAMPTRON: 2.45w
HHE
PWM: 2.1w + 0.25w = 2.35w

-[ ~2220 RPM ]-
Potential Loud Sweetspot
HHE LAMPTRON: 4.2w
HHE MOBO: 4.9w
HHE PWM MOBO DC MODE: 3.7w
HHE PWM LAMPTRON: 3.05w
HHE
PWM: 2.6w + 0.25w = 2.85w

-[ ~2520 RPM ]-
Loud But Still Sounds Good
HHE LAMPTRON: 5.5w
HHE MOBO: 6w
HHE PWM MOBO DC MODE: 4.45w
HHE PWM LAMPTRON: 4w
HHE
PWM: 3.7w + 0.25w = 3.95w

-[ Maximum, ~2900 RPM ]-
Screamer Junior Status + Garbage Efficiency
HHE LAMPTRON: 7.4w (had a bit less power, couldn't quite maintain 2900, more like 2880 or something, mobo fan would always do around 2900 to 3000, situation was same when fans were swapped)
HHE MOBO: 7.8w
HHE PWM MOBO DC MODE: 5.3w
HHE PWM LAMPTRON: 5.2w
HHE
PWM: 5w + 0.25w = 5.25w

--



Some interesting things to note.

PWM Is Indeed The Most Power Efficient
Big shocker there.

The PWM Fan Plugged Into The Lamptron Is The 2nd Most Efficient
This may suggest the PWM model fan is just more efficient than the 3-pin fan model. It's also striking how running that fan in PWM off the mobo header is only SLIGHTLY more efficient than running it in voltage control mode on the Lamptron. (Ignore the maximum speed test, as the Lamptron has less volts and couldn't maintain quite the same RPM at maximum.)

Both Fans Are More Efficient in Undervolting On The Lamptron Than The Mobo Header, But The Difference Narrows As The Power Draw Increases
It would appear for lower power fan applications, at least in the ranges I tested, the Lamptron is more power efficient for undervolting.

Comments On 3-pin Fan More Efficient On Lamptron Than Mobo
Swapping the 3-pin fan from the Lamptron to mobo, we see a consistent rise in power draw which is most striking at low speeds and smaller in % at max speed. One might be tempted to believe it's because of the lower voltage on the Lamptron, but with speeds about matched (I set the voltage setting higher on the Lamptron than on the DC mobo control to achieve the ~same RPMs) this doesn't seem to be the case.

This is hard for me to wrap my head around. It might seem like maybe, just maybe, due to imprecise RPM readings on the Lamptron, it was consistently being run slightly slower in RPM than off the mobo header, but I find it hard to believe the results would be so consistent this way. Also, the difference in power draw, % wise, is striking at the lowest speed tests. This suggests these numbers may be legit.

The % Difference Between Lamptron/Mobo in wattage goes down as the overall draw gets higher. This might suggest eventually the mobo header may overtake the Lamptron in efficiency at a high enough wattage. Perhaps the Lamptron's efficiency curve is skewed toward max efficiency at low wattage. Not a problem for me!



Thoughts/Conclusions
For a PWM fan, PWM control is the most efficient. However, running them in the 1.5w to 5.25w range from the wall, using undervolting control with the Lamptron results in a wholly insignificant loss of efficiency. Even with 5 of these fans, the difference between PWM and Lamptron undervolting would at best amount to a 1 watt total difference from the wall.

One thing I should avoid doing completely is undervolting any fan with the motherboard. At higher wattages this might be different, but clearly the Lamptron is more efficient in that regard.

As much as I love the the sound of the conventional 3-pin fan, the cost of getting to hear that motor buzz is an increase in power consumption compared to the PWM fan, regardless of whether the PWM fan is undervolted on the Lamptron controller, or controlled with PWM on the motherboard. Maybe the difference in efficiency even in undervolting is peculiar to these two nearly identical Delta models only, but it would certainly also be true in any case where two otherwise same fans are running with undervolting or PWM, though maybe the difference wouldn't necessarily be as striking. It's possible in this case the Delta PWM version of the fan was just built to a higher standard for efficiency.

If I were to run 5x of these PWM fans on the Lamptron vs 5x of the 3-pin version, at my likely target 24/7 sweet spot speeds (there's almost no chance I'd be compelled to change it unless I decided I like a different noise better), the difference in total would be 2.5 watts from the wall on the "quiet" 1740 rpm setting, 4.25 watts from the wall at my likely sweetspot setting of 2000 RPM, and 5.75 watts at the high end of my possible sweet spot settings of 2220 RPM or so. Overall, not a huge difference, though it would be a little larger if I ran all those fans on PWM. At maximum speed it would be a 10.5 watt difference. But since I'll probably never run more than 2220 RPM or so, not sure if 6 watts is worth abandoning the electric buzz.

However, maybe if I had 5x of those buzzes it would drive me nuts, with the different buzzes combining into a possible weird harmonic effect, which might have potential to be good, but just as easily would sound very annoying, unless the harmonics were adjusted just-so. The problem is minor voltage fluctuations would continually alter the harmonics of multiple electric motor buzz sounds. Running the 3-pin 1.6a SHE and the 3-pin HHE together might give me some idea of what to expect in those regards. I tend to believe the electric motor buzzing sound may sound best if it's just one distinct buzz, rather than a symphony of them. In that case, my best scenario would be just running one of those specific fans, and then just going with all other Delta PWM fans. Of course, having not tested some other Delta models or even other brands of fans, it's possible I may have other sound factors to play with before settling on the final configuration. It's very likely I will just end up running the 3 fans I ordered + the triblade 24/7, and just adding one more fan. I am not going full hobbyist here. Just trying to make things extra nice for my new build which I expect to last me as a primary system for at least 5+ years. But I need to get a move on with this, as I have other things I need to do and this is not really a project comp.

The most efficient thing for me to do would be to just go with all PWM fans. Likely it would cut down power usage 24/7 by at least 5 watts, if not more. However, this difference is not great enough to be worth abandoning the beauty and function of the Lamptron, nor the delightful sounds of the non-PWM fan models. I would predict that speed-controlling much higher power fans would make a more significant difference in which PWM, or at least more efficient PWM fan models, would be worth going with for me. However, since I just don't require much fan power, that difference won't be enough to sway me.

In conclusion, I occupy an interesting middle-ground that prevents PWM from truly benefitting me. On one hand, I run a lot more fan power and noise than quiet-computing enthusiasts and noise-haters, rendering the potential noise reduction aspect of PWM useless for me. On the other hand, I run a lot less fan power than people willing to run fans very loudly or running huge amounts of fans. The only situation in which the difference would be big enough for me, was if I was running 15+ fans, and if I was running 15+ fans, that probably means I'm at a hobbyist tier I'd only be interested in if I had my own garage workshop, which means I'd already be wealthy and I'd no longer care about shaving heat watts off my setup in a heat-trap room scenario, as I'd probably have an entire SFH at my disposal, or at least the greater part of one.