Everyone on this forum should make a duct, 10*C - 12*C drop!!!

[RoyBoy]

After reading this thread, I decided to experiment with ducting to see if I could also achieve a temperature reduction.

I made a 3.25 inch square duct tube out of cardboard and ran it from my side 80mm fan to my Vantec Aeroflow CPU Heatsink & Fan. Nothing spectacular just plain ordinary cardboard and some duct tape to close the sides. The duct was only 5.5 inches long and allowed my HSF to draw cold air in from the room rather than from inside the case.

At first I saw no advantage, as my idle temps stayed at 36*C, but after running Prime95 for two hours, I saw a 8*C drop in my load temp. To me this was unbelievable as most times, my CPU under load at 2467mhz usually runs around 52*C. Now it never exceeds 44*C. What a hoot! I love the results and will further pursue a more sophisticated and better engineered duct in the future.

Thanks to all for your precious info and advice. You all deserve a pat on the back for this one!

Merry Christmas and thanks!

 

[Cypress]

now all you need is a nice detachable duct that leads from the hole to the window. Some -5c winds and such would be quite nice huh . Then again would that work? Or would it depend on how far away the window is? I know it would work for me since my tower is about 10 inches from the window.

 

[Hookj5]

So - Question: how are you going to secure it?

My parts haven't come in yet, so I am just playing with Ideas for now. After searching onlin for a ready made adapter and not finding a 92mm-80mm I went to Home Depot and bought some stuff. an 8x10 in .093 lexan sheet, 1 fl oz of Amazing Goop which dries clear unlike all the epoxy products that were available, and a new utility knife with 3 blades. I already had a knife, but I bought a new one for the sake of starting from scratch. My total investment so far, including tax is $6.74. after I make the "fan adaptor", I should have plenty of supplies left over to make a square duct. as to where it will attach to or how I have yet to figgured out. I would like to thank voodoomelon very much for starting this thread and posting those lovely(ish) pics and for informing me of the shortcomming in my new products(SLK 900A) namely the dead spot, and a way to correct it. Thanks, I'll keep you posted on my progress and take some pictures to post here.

 

[voodoomelon]

Royboy, another satisfied customer.

So far, lets have a look.

Voodoomelon - 12*C drop
itshondo - 11*C drop
Royboy - 8*C drop
Twister1234 - 4*C drop

Lookin' good.

 

[Susquehannock]

Question: Has anyone here tried this mod with something
besides a 38mm thick Tornado fan?
If so was it really worth it?

I have seen this mod on several other forums, and in general it
has little effect unless you use a fan with high static pressure to
overcome the restriction. Results with 25mm thick fans are
usually pretty poor, and actually end up creating more noise
than it's worth.

But if you don't mind a Sunon/Vantec Tornado on high,
then this mod might be a good idea.

 

[voodoomelon]

Thing is, my Tornado is only running at 5v, which is only 2600rpm. It doesn't shift half the air it normally should, however it makes less than half the noise also.
And the fact that the Tornado is 38mm thick doesn't make a difference I don't think. If all you had was a 25mm thick fan, then simply extend the duct by the 13mm difference.
That should work shouldn't it?

 

[crull]

Okay, wait...
I must retract my original claim -> after a bit of testing, CPU idle is now 24*C, and my case temp is exactley 22.6*C at the moment.

My room temp is usually about 19*C, the ideal room temperature. I tend to keep it like that by opening the window for a minute every half hour or so -> its about 0 - 1*C outside now.
I still have to do a bit of load testing though.
And now, for some lovely(ish) pics...

I know, these temps are very much dependant on my setup, but that's what I got. But basically what i mean to say is that if anyone else ducted, they would see at the very least, a 3*C drop, because of this -> http://www.ocforums.com/vb/showthread.php?s=&threadid=248951&highlight=dead+zone

I urge everyone to give it a go, just grab some cardboard!!

OK I'm not trying to rain on your parade, but your cpu temp is only 1.5C over case temp. I find that very hard to believe. There is no way you could have a cpu temp only 1.5 higher then case temp on air according to what you posted.
I have tried this mod and I didn't notice any difference. I think there will be a difference in some cases, but its tough to say how much. I find it hard to believe it will help more then a couple of degree's though.
The fan is wasting part of its airflow by hanging off the edge of the SLK. Using this duct takes that wasted airflow and directs it to the center fins. It might also be helping because the fan is farther away from the motherboard and is getting cooler air at the intake for the fan. When the fan is close it tends to pull the warm air exiting at the bottom of the heatsink back into the fan. I know this is true because when a plain round duct is used with the case open and just about touching the fan. The cpu temp drops a bit because the warm air cant get back into the fan because its blocked by the duct. The minute you take the duct away from the fan opening the cpu temp rises a bit.

 

[voodoomelon]

Hi crull,
I accept criticism as much as praise.
But i'm telling you, that's what I was reading at the time.
Right now, as I type this, CPU temp is steady at 23*C - which is read using Gigabytes monitoring utility and the case temp is 20.9*C - read using a Lian-Li temperature probe. A difference of 2.1*C this time.
If i'm defying the laws of thermo-dynamics or some other form of physics, i'm sorry.
I don't print bogus results, the purpose of this thread is to show people what I got, and to encourage them to go about achieving the same results.

Voodoomelon.

 

[Susquehannock]

Re: Tornado fan ...

>>>>>>>>>>
And the fact that the Tornado is 38mm thick doesn't make a difference I don't think. If all you had was a 25mm thick fan, then simply extend the duct by the 13mm difference.
That should work shouldn't it?

The thicker body is to accommodate the wider, more
aggressive fins.

 

[crull]

Hi crull,
I accept criticism as much as praise.
But i'm telling you, that's what I was reading at the time.
Right now, as I type this, CPU temp is steady at 23*C - which is read using Gigabytes monitoring utility and the case temp is 20.9*C - read using a Lian-Li temperature probe. A difference of 2.1*C this time.
If i'm defying the laws of thermo-dynamics or some other form of physics, i'm sorry.
I don't print bogus results, the purpose of this thread is to show people what I got, and to encourage them to go about achieving the same results.

Voodoomelon.

I'm not trying to criticise you, but its impossible to have a cpu temp that is only 2C over case temps on air. I know Intel cpu's run cooler then AMD but there is no way that can be right.
I can run my Tornado at around 3800rpm's, with the side panel off and a big house fan blowing directly at the Tornado and the best that gets me is around 14C higher then ambient. Having the Tornado full blast might get me close to 10C over ambient, but no way 2C. This I have tested.
I don't think your knowingly printing bugus results, but I think there is a problem with your temp readings somewhere. I also know your trying to help people with what you posted. I think that duct will help, but not as much as what I've read.

 

[Real_ZERO]

i did it too.
slk947U + tornado 92

but i glued the inclined (is this a word?) sides too close to each other, and the space that was suposed to be the same wide as the slk, is a bit narrower (51MM instead of 55).

i dont know HOW bad this is

i don't see an improvement of the IDEL temp (maybe 1°c, i don't know) but when i run prime95, the temp only rises 3 or 4 °c, it used to be a little more i think

PD: there is no WAY to get cpu temp as close to AIR temp with aircooling, gigabyte mus be given a wrong temp there.

 

[3sixes]

Ok, so on mine, I didnt duct straight to the cpu, more like into the side of the case with a 120mm fan at the window side pulling in cool air from outside, and a 120mm fan on the inside of the case panel.

Right now cpu temp is a chilly 35c
My picsDafanmans Dryer Hose Mod Pics

Very simple to do, low cost, removable and efficeient.........

 

[Sniper.nkc]

Very interesting article you post. I may have to try the duct. Has anyone try to include a vortex inside the duct? A vortex in the duct will allow air to travel faster by design. Just a thought to improve concept. I am thinking of designing one.

 

[voodoomelon]

Ok, Crull has to be admired for his persistence, and has forced me to see if I have any ill temperature readings in my comp.
And, he's right.

The most obvious thing to do first of all, was to check the BIOS temp reading compared to Gigabyte's software reading, and low and behold, there is a full 5*C difference (in idle obviously). The BIOS reads, as of 5 minutes ago, 28*C. And after booting into Windows, the Gigabyte software read 23*C.

To ensure the Lian-Li probes were functioning properly, I put both of the probes in the same position, and both read the same temp within .1*C of each other -> 20.6*C. I also put a food thermometer in the case, and it read 20.4*C. So no problems there.
Alot of people always thrust only the higher of two temp readings, in this case the BIOS. This is the one I will be looking at from now on.

But this slight discrepancy does not make the temp improvements of the duct false or invalid. The fact is, there is still a 10*C - 12*C drop. Gigabytes software read ~34*C idle before I put in the duct, and now 23*C after installation, despite the fact that it tends to read at 5*C less than the BIOS. I always remembered the BIOS temp being in the 40's whenever I went into it in the past.

I thank crull for making me scrutinise my own work.

 

[TheWesson]

I agree - I bet it does have a lot to do with the CPU fan not "rebreathing" the hot air it pumps out.

The 10C drop would imply then that the air the CPU breathes is 10C lower.

Sounds about right - now it breathes 20C, it used to breathe 30C from its own exhaust?

It's the equivalent of having a better ventilated case.

Now if you already had a maximally ventilated case, and you used this fan shroud mod, and your CPU temps dropped by 5C, then you'd have to ascribe that temp drop to the shroud affecting airflow patterns through the heatsink.

I'd suppose that the shroud does make better airflow throught the heatsink, but the main effect is avoiding the rebreathing and thus (from the CPU's point of view) having a better ventilated case.

the wesson

 

[crull]

Just so I have some idea as what your true temps are because I lost track. Please post your ambient temp, case temp and cpu temp.

Usually ambient temp is the starting point and case temp can never be lower then that. A Perfect case temp would be equal to ambient temp, but thats just about impossible. The air surrounding the case temp thermistor can not be cooled fast enough. Or at least it seems that way. If you open your case and blow a fan right on the thermistor it still always seems to pick up a little bit of heat from the surrounding components. The best I have seen is the thermistor reading the case temp 1.5C higher then ambient.
Now as far as CPU temp goes. For one thing your overclocking as am I. So I don't think you will ever get a lower cpu temp then 10C above ambient on air cooling. Intel cpu's generally run cooler then AMD, so in your case that 10C might be more like 8C higher then ambient, but I doubt any better then that. This is based on very specific testing that I have done.
Your using the same heatsink and fan that I am. I ran the Tornado at 3750 rpm's and had the side of the case open with a house fan blowing ambient temp air right into the intake of the Tornado my cpu runs about 14C higher then ambient. If the Tornado was running full that might be maybe 10C higher. I have tried your duct with the case open and it didn't make any difference, but maybe I don't see any difference because my Tornado is already ducted to outside.
I have a Smart Fan 2 in the side of my case right over the Tornado. There is a square duct between them. I have the thermal probe running the smart fan so as the cpu gets hotter the Smart Fan feeds the Tornado more air. Maybe if I didn't have that duct and were using just a closed case your mod might have made a difference. I added a potentiometer to the thermistor on the smart fan so I can control how fast the smart fan spins based on what the thermistor reading is.

 

[legelf]

I like the idea of a duct between the HS and fan but I'm not tocrazy about the corners of the duct. The solution I've comeup with may be a bit time consuming but my look and fit better

currently I work in a glass shop with access to all diferent thicknesses of plexi and lexan. A few days ago I saw a chunk of 1.5" thick lexan in the cutoff box. It caught my eye because usually I don't see 1.5" around. Today after reading this thread it hit me...drill a 3.5" hole in the center of the lexan then drill the mounting holes for the fan along the edges. Polish it up and it would be a thing of beauty. Mounting with the supplied clips from the SLK wouldn't be a problem either...just drill some 1/16" holes in the sides on a downward angle...modify the clips to slide into these holes.

As for makeing plexi pliable just put it into the oven on a low setting for a few minutes then form it to whatever shape you want. eg. wrap it around a cylinder to create a tube. Joining the end is no problem either just use some MEK (methal ethal keytone *caution* extremly poisonious keep area well ventilated) to weld the end together.

Just my two cents.

 

[voodoomelon]

Hey.
Ok, things are a little heated up at the moment in this room, I haven't had the window open, and there has been 3 people in the 14' X 9' room for the last 2 hours. So, my temps at the moment are as follows:

Ambient room temp : 20.8*C
BIOS CPU temp: 29*C
Case temp 23.9*C

CPU Torando: 2556rpm
2x 80mm intakes
2x 80mm exhausts
1x 80mm intake blowhole over Radeon
1x 80mm exhaust top of case

My room temp is usually ranging from a chilly 15*C to a warmer 20*C, on average about 18*C i'd say.

When the room is 18*C:
BIOS CPU temp: ~ 28*C
Case temp: ~ 22*C

Crull,

So I don't think you will ever get a lower cpu temp then 10C above ambient on air cooling.

Can't say I agree with that. I'm sure there's probably plenty of people with CPU temps lower than 10*C over ambient. I don't doubt for a second that you've done extensive testing, however have you done it on more than one machine in different locations?
The temperature outside me right now is easily -2*C. Does this count as a sort of ambient temp for this room? The insulation in this house leaves alot to be desired, hence my usual low temp of 14*C when I wake up. Also, opening my window every half hour or so when it heats up leads to a difference in air pressure. That would also affect my case temps.

I don't know what else I can say to convince you crull.
"them's my temps an' i'm stickin by 'em"

I'm just trying to highlight the differences between our setups.

 

[itshondo]

My Update-

Temps have stabilized about 5c less than they origionally were. My next step is to remove my Panaflow fan from the duct and relocate it (or a tornado) to the door of my Antec case. Then I'll connect the fan to the heatsink duct with some 4 inch duct. I'm planning on making 4 inch duct adapters out of 4 in roof stacks. The only thing holding me up is I'm waiting for a 92mm fan filter and tornado to come in(the SLK-900 clogs easily with dust) -

Still waiting pr the photos of the duct to come in..

 

[vkvenom]

voodoomelon Use pipe thread sealer for pvc pipe or plastic same stuff plumbers use!