Push/Pull configuration

[prasvt]

So my Swiftech 2 x 120 rad is configured such that the top 120 is pulling (due interference w/ the psu power plug) and the bottom fan is pushing...both are 2000rpm rdm1225s fans. I added TT 1225 120mm to the front of the bottom part of the rad for a push / pull config. Just curious about whether the two fans need to be running around the same speed. I'm pretty sure that the TT fan is only running at 1400rpm at 12V and I ordered a 2100rpm 86.5cfm Panaflo fan that should match it, as the rad fan seems to favor 2140rpm while the top rad fan actually stays at 2000.

So ... does it help to have the fans running at the same speed? I would claim that my temps have dropped 1 or 2 C but it's also gotten much cooler outside, so not sure I'd be accurate.

Right now, my Q6700 is at 3400mhz @ 1.48V and at idle Realtemp reports 30/30/29/32 across the four cores. ~50C midday at full load.

 

[BillParrish]

Lots of history on if push/pull is worth the effort, concensus was it helps a tiny bit but not (in general) worth the expense with the biggest issue being the room it took. But I dont remember anything with discussion about have one of the two paired fans at a different speed. I dont think its going to matter a lot and have a hard time figuring out how it would significantly hurt anything. You have a matching fan on order so I would not be worrying about it and if you measure/record accuratley now, you will be in a postion to answer your own question when the new fan shows up and let us know the answer.

 

[TehQuick]

imo, push-pull good with 'thin' fans, in other words, two 25mm fans work as well as one 35mm fan.... That's my justification, anyways

 

[prasvt]

Well I'm not so much concerned about the room it takes or the noise. My top radiator fan is in pull mode b/c otherwise it was obstructing the psu plug. The bottom fan is in push mode and it dawned on me that I could mount another fan on the outside since there was space. It could be helping though...I ran prime95 smallffts for about 9 hrs last night at 3.6ghz (~1.5vcore, ~1.47 under load) and right now idle temps are 29-30C across the 4 cores ...~52C under load. That's amazing considering prime95 failed on core 3 or the computer just bsod'd when I was using air cooling w/ the Tuniq Tower.