CPU Power Cable, Also My Favorite Kind

Thermaltake Smart-M 750 W Power Supply Review

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Here we have Thermaltake‘s entry into the mid-wattage, modular, low price, PSU market. Will it succeed? Will it explode? Will it descend into a mire of mediocrity or rise to the pinnacle of superiority? You’ll see soon enough, if you keep reading.

Features and Specifications

In the interest of not causing undue pain and suffering, I’ll be using box photos for this section. My comments will be under the photos.

ttsm750-s-f-Features1

So far, I like what I see. The Japanese Main Capacitor line makes me especially happy, it’s far more honest than the usual “Japanese Capacitor!” line many manufacturers use.  I do find it mildly amusing that they have a photo of the 5 V / 3V3 DC-DC controller rather than the protections IC, but whatever. The fan is definitely nice and large, I like screens like that better than wire finger guards. Screens keep screws and cables out. DC-DC for secondary rails is great, if the pic is accurate this is almost certainly a CWT design. Flat modular cables are my favorite sort for use, if not the prettiest. Given the modular cables, the lower right picture seems excessive, though it is nice to know there’s somewhere to plug the cables in.

ttsm750-s-f-Features4

100% Japanese capacitors is a more ambitious statement than the first photo had, other than that we have pretty much the same information. We do get a temperature spec here though, 40 °C is solid, if not “yay!” worthy.

ttsm750-s-f-Features2

As usual for DC-DC PSUs we can draw almost the entire unit wattage on the 12 V rail. The combined 5 V / 3.3 V is a bit lower than the normal 150 W, but it’s still plenty high. Cable wise we appear to have a good selection, no issues there.

ttsm750-s-f-Features3

Last for the box are a pair of graphs showing theoretical efficiency at 115 V and 230 V input levels, as well as the fan speed. I seriously doubt that the fan is actually controlled by load, I expect it’s heat based and the curve they show there assumes a given intake air temperature. The noise numbers look refreshingly honest.

Photos Part One: The Box

The Box, Front Side

The Box, Front Side

Rear Of The Box, Look Familiar?

Rear Of The Box, Look Familiar?

Box Open!

Box Open!

Box Open, Manual Removed. There's A PSU In Here!

Box Open, Manual Removed. There’s A PSU In Here!

The PSU has some heavy duty bubble wrap on it, but not as much protection as I’d really prefer. It survived shipping fine though and that’s what matters. I’ll take it out and take more pictures!

Photos Part Two: The PSU

Fan Side

Fan Side

Label Side, Ultra Got Paid

Label Side, Ultra Got Paid

Electrical Output End

Electrical Output End

Air Output End

Air Output End

One Side, The Other Is Extremely Similar

One Side, The Other Is Extremely Similar

A (Bad) Angled Shot

A (Bad) Angled Shot

I don’t know what my cameras problem was, but it did a horrendous job of the other pictures I took. So it goes. In any event the PSU is pretty nice looking, crackle-black paint and the labels you see above. It’s a bit heavier on marketing than I’d prefer, as by the time you see it you probably already bought it. Not a huge issue though. The cable map on the output end isn’t especially needed, but I’d rather have it and not need it than the other way around! That shiny sticker means that Thermaltake paid Ultra for their now-defunct (rejected a couple years ago) patent on modular cables, if you were wondering.

Photos Part Three: The Cables

ATX24P Cable, My Favorite Kind

ATX24P Cable, My Favorite Kind

Modular Cables!

Modular Cables!

CPU Power Cable, Also My Favorite Kind

CPU Power Cable, Also My Favorite Kind

The ATX24P and CPU power cables are both of the sort that you can disconnect four pins of, they’re my favorite kind too. They clip together so you don’t have the chase the small part around with your fingertips and try to get it lined up with the socket. They un-clip easily too. The modular cables are as described previously, flat ribbon sorts. We get a pass-through Molex-FDD adapter, I like that better than the sort that consumes the Molex entirely. So far the box has proven to be very honest, I approve!

Testing Part One: Regulation Testing

A decent load test of a PSU requires a decent load. Contrary to what some may believe, that means you need a known load that can fully stress the PSU. Computer hardware does not cut it. Worse, if the PSU fails during testing it might take out the computer hardware anyway. Commercial load testers cost a lot of money. I do not have a lot of money, so I built my own with juicy power resistors and a Toyota cylinder head. It works great. I’ll be using it to load this thing down fairly severely and will check voltages and ripple (more on that later) at various points. The down side to my tester is that the loads it can put on PSUs are fairly coarse, they go in increments of 48 W for 12 V, 50 W for 5 V and 22 W for 3.3V. Those wattages assume the PSU is putting out exactly the official rail voltage, a PSU putting out 12.24 V rather than 12 V will be at 49.9 W per step rather than 48 W. I file that under the “tough beans” category as I figure if a percent or two of load makes that much of a difference, the PSU manufacturer should have hit the voltage regulation more squarely. It does make calculating efficiency difficult at best.  However, given that the input power is read via a Kill-a-Watt, the efficiency numbers are dubious to begin with. Kill-a-Watts are not known for extreme accuracy on things with automatic power factor correction. For this reason, I am not listing the efficiency.

The ATX spec says that voltage regulation must be within 5% of the rail’s official designation, regardless of load. It doesn’t actually mention that the PSU shouldn’t explode, though I expect they figured it was implied. Exploding is a failure in my book regardless.

It is also worth knowing that I will be testing this PSU at both outdoor ambient temperatures (typically between 10 °C and 20 °C here this time of year) as well as in the Enclosure of Unreasonable Warmth. TEUW is a precision engineered enclosure that I use to route the exhaust air from the PSU right back into the intake fan, it is adjustable to hold the intake air temperature at (almost) any level I want it. This way I can test the PSU’s response to hot conditions as well as cold conditions. For the hot testing I will be running the intake temp as close to the unit’s maximum rated temperature as possible. TEUW, in case you’re curious, is a cardboard box.

Wattages (total) 12 V Rail 5 V Rail 3V3 Rail Kill-A-Watts Temps In/Out
0/0/0w (0w) 12.27 5.08 3.34 13.7 8/11 °C
96/50/22w (168w) 12.26 5.06 3.32 198 6/10 °C
288/50/22w (360w) 12.27 5.05 3.32 413 6/14 °C
480/50/22w (552w) 12.23 5.05 3.31 636 6/19 °C
672/50/22w (744w) 12.18 5.05 3.31 868 7/27 °C
HIGH TEMPERATURE RESULTS BELOW:
672/50/22w (744w) 12.13 5.04 3.31 883 45/58 °C

If you’re paying attention you’ll note that I violated the 40 °C spec (wasn’t paying enough attention, oops). The PSU didn’t care though.

12 V regulation came in at 1.1%, very good and just shy of the magical 1% number. 5 V regulation killed it at 0.79% regulation, very nice indeed. 3.3 V managed 0.9% regulation. That gives us a grand total of 0.97% regulation, excellent!

At idle and low loads the fan made some airflow noise, not a lot, but some. As the loads ramped up the fan did as well, it didn’t change a huge amount until a fairly high load due to my low ambients. At full load it’s not exactly quiet, but it’s not horrendous either. There’s a bit of a hum and a fair amount of airflow noise, if you’re building a system based on silence and are running quiet CPU/GPU coolers, you’ll hear this PSU at full load. If you’re using anything resembling stock/reference coolers they’ll drown it out easily.

Out of brutality I decided to test the short circuit protection. It works better than any unit I’ve tested before, minimal damage was done to my SCP test equipment before the PSU shut down. Very good!

All told, I’m rather impressed.

Testing Part Two: Ripple Testing

Ripple is fluctuation of the PSU’s output voltage caused by a variety of factors. It is pretty much impossible to have zero ripple in a SMPS computer power supply because of how a SMPS works, so the question is how much ripple is there? In the regulation testing phase we found out how the PSU does at keeping the average voltage at a set level, now we’re going to see what that voltage is doing on really short time frames. The ATX spec says that the 12 V rail cannot have more than 120 mV peak to peak ripple, the 5 V and 3.3 V rails need to stay under 50 mV.

If that isn’t complicated enough for you, there are three forms of ripple to keep track of as well. Long-term ripple from the PSU’s controller adjusting the output voltage and over/undershooting, correcting, overshooting, etc. Medium-term ripple from the voltage controller charging and discharging the inductor(s) and capacitor(s) that make up the VRM, and very short-term ripple caused by the switching itself. The first and second forms are the most important, if they are out of spec it can cause instability at best or damage in extreme situations. The very short-term (I call it transient ripple) flavor is less crucial, excessive amounts can still cause issues though it takes more of it to do so. The ATX spec does not differentiate, as far as the spec goes 121 mV of transient ripple is just as much of a failure as 121 mV of medium or long term ripple.

I test ripple in a few difference ways, first I test it during the cold load testing. It is tested at zero load and maximum load first. During the hot load testing I test the ripple at maximum load again. I have recently started testing ripple at fairly random loads with the unit still hot, it’s a bit unorthodox (a bit? maybe a lot) but has found issues in the past that did not show up with other test methods.

For this first batch of photos the scope settings are 10 µs / 10 mV for the 12 V shot and 5 ms / 10 mV for the 5 V and 3V3.

12 V Ripple, cold, zero load, scope @ 10 µs / 10 mV, ~18 mV of ripple

12 V Ripple, cold, zero load, scope @ 10 µs / 10 mV, ~18 mV of ripple

5 V Ripple, cold, zero load, scope @ 5 ms / 10 mV, ~30 mV of ripple

5 V Ripple, cold, zero load, scope @ 5 ms / 10 mV, ~30 mV of ripple

3V3 Ripple, cold, zero load, scope @ 5 ms / 10 mV, ~30mV of ripple

3V3 Ripple, cold, zero load, scope @ 5 ms / 10 mV, ~30mV of ripple

12 V looks great at 18 mV, the other two are both a bit higher than I’d really like to see with no load, but within spec at 30 mV.

All the rest of the scope shots are at 5 µs / 10 mV. Next up are full load, cold ambient, shots.

12 V Ripple, cold, full load, scope @ 5 µs / 10 mV, ~72 mV of ripple

12 V Ripple, cold, full load, scope @ 5 µs / 10 mV, ~72 mV of ripple

5 V Ripple, cold, full load, scope @ 5 µs / 10 mV, ~52mV of ripple

5 V Ripple, cold, full load, scope @ 5 µs / 10 mV, ~52mV of ripple

3V3 Ripple, cold, full load, scope @ 5 µs / 10 mV, ~62 mV of ripple

3.3 V Ripple, cold, full load, scope @ 5 µs / 10 mV, ~62 mV of ripple

12 V is well within spec at 72 mV, though higher than ideal. Still, I’ll call that “good” ripple control. 5 V is 2 mV over spec, I’ll let that slide as that’s within the margin of error for my equipment. The 3.3 V rail is 12 mV over spec, which I can’t let slide. It’s extremely unlikely that it’ll cause problems, but the spec is the spec.

Lastly full load and 40-45 degree intake air temperature shots.

12 V Ripple, hot, full load, scope @ 5 µs / 10 mV, ~62 mV of ripple

12 V Ripple, hot, full load, scope @ 5 µs / 10 mV, ~62 mV of ripple

12 V Ripple, hot, full load, scope @ 5 µs / 10 mV, ~46 mV of ripple

5 V Ripple, hot, full load, scope @ 5 µs / 10 mV, ~46 mV of ripple

3V3 Ripple, hot, full load, scope @ 5 µs / 10 mV, ~54 mV of ripple

3.3 V Ripple, hot, full load, scope @ 5 µs / 10 mV, ~54 mV of ripple

12 V ripple dropped 10 mV, putting it just over half spec, still what I’d call good. 5 V dropped 6 mV and is firmly planted within spec now, 3.3 V dropped a bit too, but at 54 mV is still just outside what I’ll accept as within spec. 4 mV over spec is not going to cause an issue, but the spec is the spec.

The ripple results are disappointing after the extremely good regulation, but they aren’t bad enough to cause issues by any means.

Let’s rip this thing apart.

Dissection

Disclaimer: Power supplies can have dangerous voltages inside them even after being unplugged, DO NOT OPEN POWER SUPPLIES. It’s just not a good idea. Opening a power supply and poking around inside could very well kill you. Don’t try this at home. Don’t try this at work. Just don’t do it.

Popping the lid off we’re greeted by the fan and various internals, here arre pics!

Fan Hub

Fan Hub

Internals Overview

Internals Overview

Overview Number Two

Overview Number Two

Definitely a CWT unit, CWT has run the entire range from highly “meh” units all the way up to the awesomeness of >1200 W 80+ Platinum units. Lately I’ve seen them put out a number of different very nice units. For reference, this is almost exactly the same platform as the Corsair TX750m, though that PSU uses schottkys for the 12 V rail rather than MOSFETs in this one. Our detailed tour kicks off with the transient filter:

Transient Filter, Part One

Transient Filter, Angle One

Transient Filter, Angle Two

Transient Filter, Angle Two

Four Y caps, two X caps, two inductors, fuse, TVS diode, this is a nice complete transient filter. Next, the APFC!

One of Two Primary Rectifiers

One of Two Primary Rectifiers

APFC MOSFETs

APFC MOSFETs

APFC Diode

APFC Diode

APFC Capacitor

APFC Capacitor

APFC Controller

APFC Controller

Two GBU606 (6 A, 600 V) rectifiers deal with the incoming AC, after that a classic CM6800TX APFC/PWM controller uses a pair of K20J60U (20 A, 600 V) MOSFETs and a QH08TZ600 (8 A, 600 V) diode to boost the voltage to ~380 V and store it in the Panasonic primary capacitor. Once that’s been done, we move on to the primary MOSFETs:

One of Two Primary MOSFETs

One of Two Primary MOSFETs

5VSB MOSFET

5VSB MOSFET

The primary MOSFETs are a pair of P18N50C  parts that I was unable to find information on. If they follow standard conventions they’ll be 18 amps and 500-550 volts. The 5 VSB rail gets a HFS3N80 (3 A@25°C, 1.9 A@100°C, 800 V).

On the secondary side we have synchronous rectification:

12 V Rectifiers

12 V Rectification Board

One of the 12 V rectification MOSFETs

One of the 12 V rectification MOSFETs

12 V gets a total of six AP9990GH-HF-3(100 A@25°C, 70 A@100°C, 60 V) MOSFETs on a daughterboard.

The 5 V and 3.3 V rails are generated on the modular connector board:

Modular Board, Plug Side

Modular Board, Plug Side

Modular Board, Solder Side

Modular Board, Solder Side

5 V and 3V3 DC-DC VRM Controller

5 V and 3V3 DC-DC VRM Controller

One of Three MOSFETs On 5 V

One of Three MOSFETs On 5 V

The APW7159 brainbox runs both rails, each rail gets three AP72T03GH (62 A@25°C, 44 A@100°C, 30 V) MOSFETs.The 5 V and 3.3 V rails each get a pair 1500 µF polymer capacitors, given the ripple we saw in the previous section this isn’t quite enough.

There’s some copper EMI shielding between the inductors and the PSU case:

EMI Shielding Between Inductors and Case

EMI Shielding Between Inductors and Case

5 VSB rectification is done with a single 1040CTP (10 A, 40 V) Schottky diode. Protections on the 12 V rail are via A WT7502V, 5 V and 3.3 V protections are build into their DC-DC brainbox.

The soldering is of very good quality, no meaningful issues are to be found:

ttsm750-diss-soldering1

Soldering

All told, it’s a well-built PSU. All the electrolytic capacitors are indeed Japanese too! refreshing.

Final Words and Conclusion

This is a solid PSU!

The voltage regulation is excellent for the price range, and very good on any price range really.

The ripple control on the 12 V rail is good, on the 5 V rail it’s decent, but on the 3V3 rail it’s over spec. Not by a lot by any means, but over. I would be extremely surprised if it caused issues.

The cable selection is solid for a 750 W unit, four PCIe plugs is all you’re likely to need unless you’re running a bunch of low end GPUs, in which case there are enough Molex plugs to fill in.

The fan isn’t fantastic, a quieter unit at fan loads would be nice.

The looks I like overall, I could do with a bit less advertising on the case itself, but that’s a minor gripe. I definitely like the grill style fan guard rather than the standard wire guard, while it makes more airflow noise it also keeps screws and cables out.

The marketing on the box turned out to be honest and accurate, with the possible exception of the “Ultra quiet” fan. It’s not bad, but I wouldn’t call it Ultra Quiet. On the other hand I appreciate Thermaltake using “Quiet” rather than the “Silent” many brands use. Much more accurate.

Build quality, component selections and soldering are very good, no issues there.

The price is currently around $90-$95 online, depending on the store. As of last week Newegg listed it at $89.99, now it’s listed at $115 with a 20% discount code in the listing, making for $92. Newegg loves to play these games with prices. I’m going to pin the price at $95, as there are a number of reputable stores online selling it for that price.  At ~$95 it is very good deal, similar units run from $90 through $120. Whether the $90 units have all Japanese caps and such I don’t know, the units that I know are of the same quality or better are in the $100-120 bracket. Even going by Newegg’s price, this PSU is a good value. Going by low-average online pricing it’s a very good value. What Newegg is smoking with regards to this PSU wattage/efficiency bracket is beyond me, the prices made a lot more sense last week than they do this week.

All told there are plenty of pros:

  • Handles 750 W at 40 °C easily.
  • Excellent regulation.
  • Plenty of cables.
  • Very good build quality.
  • Good price/value.
  • Honest box marketing.
  • Grill style fan guard keeps dropped screws and cables out.

There are a few cons too:

  • Fan could be quieter.
  • Violates ripple spec on the 3V3 rail by 6-12 mV.

All told this Thermaltake Smart-M 750 W power supply easily earns the Overclockers.com approved badge.

ocapproved(Click the Approved for a description of what it means)

— Ed Smith / Bobnova

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Discussion
  1. Bobnova
    Not really, the leads that come out the bottom will poke through most rubber gloves quite easily. Very very sharp.


    +1 to that i almost always have scratches on my knuckles from those damn sharp things lol mostly from motherboards
    Same platform (more or less, a bit more advanced actually) as the Corsair TX750m. That's the general quality level too. I expect the corsair unit to have the exact same ripple issues as I've tested at two of these smart-m 750w units now (not as part of this review, just randomly) and they both had almost exactly the same 5v/3.3v ripple. From pictures the DC-DC bits are 100% identical between this unit and the Corsair.
    TL;DR version: Solid PSU, neither the mire nor the pinnacle.

    Definitely worth considering if the price is right at the moment you need a PSU.