water cooling...seems a bit high still?

[therapture]

Here is my setup:
-12"x5" Hayden trans cooler
-(2) 120mm fans at 85cfm each at 12v
-BeCool "maze" copper block
-Danner 350 Magdrive pump
-3/8" fittings throughout
-water with 10% antifreeze mix
-ambient temps of 24c

With an 81 watt load (1.0ghz at 1.21ghz with 2 volt core) I am still hitting temps of
41c-42c under an extended load. I have good water flow, the block has thermal grease on it, and there is PLENTY of airflow in the case and through the radiator. I have also checked for a square fit on the block /cpu interface and it seems perfect! If I turn the fans down to 10v for quietness, I hit temps of 44c.
Where am I getting this high temp? At that temp, my effective C/W is only in the .21 range, rather high for a water cooling setup.
Something seems amiss....not too mention at LANS the ambient temp is often in the 27c-29c range an that puts me in the 45c-48c on the cpu temp and I just don't like that at all.

I am at 100% perfect stability, but my temps seem a bit to the high side, even at the wattage I am pushing. Any suggestions?

P.S.---the water goes from pump to radiator, to reservoir, to waterblock, and back to pump. Pump is inline closed loop, so no heat from pump is contaminating the results. See the pics at

http://therapture.is.dreaming.org

 

[AMDGuy]

I've read that anti freeze actually degrades the heat carrying capacity of water. I recommend either running straight water or "Water Wetter" as this will give you more preformance.

 

[Murphy]

Seems like your fans don't pull the air through the full surface of your radiator. Does your liquid feel warm? You have a perfect block, I made one myself. I use a bigger radiator, a heater core from a '77 ford. These have LOADS of surface. Too bad I don't have a digital camera. Hope I can borrow my friend's one...
And I have to admit your ambient is a little bit high, so your temps will be up also a bit.

 

[Fink]

I would not be concerned with the 10% antifreeze, it will not degrade the thermal performance of the water to a noticable degree.

Sounds like you are not getting enough air over the radiator as per Mr Murphy. Where is the rad located, external? Internal?

Did you check the flowrate of you pump after setting it all up?

 

[therapture]

Actually, the two 120mm fans cover the entire radiator surface....even on the edges it is right on the money. I am suspecting the cpu to block mating. The block is flat, but perhaps the clamps on each side are off just a bit...it would not take much difference to make the block "rock" a bit to one side, even though it may still be touching, the clamping pressure would be quite a bit different from one side of the cpu to the other, and that can surely affect temps. I am going to delve into that before I do any rerouting of tubing.
And FYI, a 10w, 20 ohm ceramic resistor from Radio Shack ($0.99 for two) is PERFECT to step down the fans. I will have to put a voltmeter on it tonight to check the actual voltage drop, but the fans are pushing more air than at 10v but almost as quiet. I simply wired it inline, and it feeds both fans nicely. (I only used one resistor shared between fans).

 

[therapture]

Fink (Apr 17, 2001 03:04 p.m.):
I would not be concerned with the 10% antifreeze, it will not degrade the thermal performance of the water to a noticable degree.

Sounds like you are not getting enough air over the radiator as per Mr Murphy. Where is the rad located, external? Internal?

Did you check the flowrate of you pump after setting it all up?

The radiator is internal
The two 120mm fans are in the top of the case, blowing ambient air INTO the radiator which is attached to the fans...look at the pics at http://therapture.is.dreaming.org

I have TONS of airflow through the radiator, you can feel it blowing inside the case rather freely....and two 80mm fans take that air and toss it out the back of the case so it does not heat up the interior. Case temps have never exceded 31c...and the radiator is not getting case air, it comes from outside.

 

[coldmop]

restict the flow for an hour or so. Small C- clamp on hose or a valve if you want to drain. Even vice grips with padding will work. Try to cut flow about half.

 

[therapture]

OK...I have found the cooling culprit! I broke out the digital temperature gun (highly accurate) and measured some temps around the system. First of all, my ambient room temp is actually about 26c, give or take 1c either way. AND, the water temps under load are hovering at 30c. I measured the fittings, the hoses, the reservoir, and the radiator. ALL were 30c to 30.5c. NOW, taking into consideration the 30c water, the 12c delta (42c loaded) is right on target.
My cpu is at 81.8 watts, so taking that, we plug it into the formula...
Delta=C/W X Watts....or, knowing the delta...12=C/W X 81.8 = .146 (12 divided by 81.8)

Delta + ambient (in this case the water) = loaded temp of cpu

Now, add that to the water temp of 30c, and voila! 42c loaded temps. Since we all know that your cpu temp is derived from the temp of the medium by which it is cooled. So....a C/W of .146 is RIGHT on for an average watercooling setup.

Now the trick is to figure out how to make my room match the rest of the house in temperature because my room, having 3-5 computers in it at all times, essentially has heaters going in it constantly.

So anyway, my heart is happy that the watercooling is doing just what is was designed to.

Now, my room temp....whew....