CPU & coolant temp differences between min & max airflow?
 

Hi guys,

For WC-setup details see my sig.
My CPU temps (from on die diode) and coolant temps (from 10K NTC after radiator and fishtank thermometer in airtrap) only decrease 1 to 1.5°C when I increase the radiator fan voltage from 6.5V to 12V (independent from ambient temp and CPU load, I get always a decrease of 1 to 1.5°C).

Does that mean my radiator can't cope with the increased air flow (heat exchange does not increase much more)?
Or does that mean my rad is so good that almost maximum heat exchange is achieved with lower airflow?
I'm a little confused by the tiny temp delta...

For memory, my rad is the (now obsolete) BeCooling AquaCoil II .
It's a cube style rad with two 3/8" parallel waterways of 10 passes each and 1/2" connections. The 86CFM Panaflo M1A is sucking air through a 1.5" shroud and radiator air intake is separated from the case.
I first used a Panaflo L1A (for silence) and I thought airflow was too low.
http://www.turbokeu.com/mycomputer/pc-70/pict0072.jpg

Motherboard Monitor Idle (Ambient temp=25°C and Panaflo M1A radiator fan at 6.5V). CPU was running 2250MHz at time of picture.
http://users.skynet.be/turbokeu/myco...bm5.3-idle.jpg

Idem 100% CPU load with Prime95 Torture test after half an hour (coolant temp oscillated between 26 & 27°C).
http://users.skynet.be/turbokeu/myco...bm5.3-load.jpg

Could you please post your thoughts, and if possible your temp differences between min & max airflow?
Thanks,

CD :)

I don't think it matters with your setup, you have isolated the hot air from the computer. I think most of the cooling actually comes from the water running through the radiator itself... try running it WITHOUT your fan on and see what happens.

Any way you put it though I think you are very lucky.

If your temps are accurate, then you've got ~2 deg difference, between ambient and the water temp (+/- 2 or 3 deg), which is excellent. What did you do to that Aquacoil? ;)

Otherwise, the problem isn't with the rad, it's with the fan: the axial fans aren't able to produce a lot of pressure. Also, your airflow direction acts as an added restriction.

Wait until I've got my blower up and running: you'll see ;)

I didn't do anything to that AquaCoil...:p

What do you mean by "your airflow direction acts as an added restriction."?
Here's a pic of the outtake of the rad (without the intake shroud to the top panel):
http://www.turbokeu.com/mycomputer/pc-70/pict0009.jpg

CD :)

Edit: I just realize that my daily glass of white port is visible in the background... :D

Oh! I thought it was a top-mounted fan! You're all set.

If the fan was top mounted, then the incoming air would have to turn 90 degrees, and that being right after the fan, is pretty bad for flow. Axial fans are pretty touchy that way.

I can't think of a way to optimize the air flow here: you're got it "spot on!". The M1A is a perfect choice. :shrug:

I'd consider using a blower, but I'm not sure that a 4" blower would outperform those M1A's either for flow or noise.