Direction of CPU fan

owain_thomas · Post by **owain_thomas** » Mon May 19, 2003 2:22 am

I have a Zalman flower heatsink on my AMD 1600+, this sits just below the air intake on my (currently quite noisy) 2-fan Q-Tec PSU, the case I have has one exhaust fan mounted on the side panel (right in the middle) blowing out of the case.

My question is which is the best way for my CPU fan to blow? At the moment it is blowing down onto my CPU, meaning presumably that the hot air from the CPU is then taken straight into the PSU, would it be better to have it sucking away from the CPU and having this hot air exhausted from the case via the side panel.

Thanks
Owain

Post by **Ralf Hutter** » Mon May 19, 2003 4:54 am

Most heatsinks (including your Zalman) are designed to have air blown down onto them. Alpha is one exception to that rule, they are designed to have air sucked through them.

You'd need to try your CPU fan in each direction while monitoring your temps to see what works best in your system.

silencio · Post by **silencio** » Mon May 19, 2003 10:40 am

Even Alpha heatsinks require experimentation.

Flow towards the heatsink works better than flow away for both the Alpha FC-PAL15 and FC-PAL35.

Zhentar · Post by **Zhentar** » Mon May 19, 2003 11:52 am

I've found that blowing into the heatsink can work better; but using ducting and pulling away can work very well too.

Best is to simply try it both ways though.

mynci · Post by **mynci** » Mon May 19, 2003 1:45 pm

i had a similar setup, i find that havng the fan blow on the hs an then block the qtech's lower hole (remove the fan) and put a panaflo instead of the remaining fan (mines controlled by a ecternal speed controller, bypassing the thermal control) not i get good cpu temps and much better psu exhaust temps.

i may try to duct the cpu hsf out of the exhaust if time permits.

BillyBuerger · Post by **BillyBuerger** » Tue May 20, 2003 7:27 am

I had a volcano 9 HS with a panaflo L1 on it. I reversed the fan to blow away from the HS and ducted out the back and it stayed just as cool if not slightly cooler. I now have a Thermalright AX-7 again with the reverse fan ducted out.

I figured since I had an exhaust fan right next to the HS fan that I was using two fans to 1) remove the heat from the HS and 2) remove the hot air from the case. Why not just use the 1 to do both.

Anyways, I'm happy with it.