Does placement of fans matter?

[kokin]

So this may be a weird question, but here goes: Would the placement of different fans on a HSF have any advantages or disadvantages?

I currently have a Scythe Mugen 2 cooling my PhII 955 and I'm using a 90 CFM Yate Loon fan as a push fan and the stock (74CFM) fan as a pull fan in conjunction with my Antec 902's rear 120mm. Would it be better to have a stronger push fan or a stronger pull fan? I have another 90CFM YL fan, so would having 2 equivalent fans be better than having a stronger pusher/puller setup?

I know that CFM doesn't directly affect temps, but I always wondered about the pressure produced by different-rated CFM fans.

 

[jsc]

I think the mismatched fans are interfering with the airflow through the heatsink.

I'd remove the lower rated pull fan and see if that had any effect on CPU temps.

Back when I bought my TRUE, I chose Scythe S-Flex SFF-21F fans to go with it. I oriented the HSF vertically to take advantage of the large fan on top. I also tried a push-pull configuration, but testing indicated no significant decrease in CPU temps.

All I can suggest is additional testing to see what actually yields lower CPU temps.

 

[Mugz]

If you are going to fit multiple fans in a push-pull set up, it is best to make sure that they match - same CFM and so on. Otherwise they interfere with each other and produce more noise and vibration.

 

[fleakiller]

Plus one for Mugs

 

[blakeyon2asd]

Yeah of course it matters, here's what I always try to tell people building computers that involves 3 or more fans. Always keep the lower one(s) pulling air that way the cool air will rise thru. For the rear fan(s) always keep them blowing how air out because heat rises they will be most effective that way. If you have front fan(s) keep them sucking air in no matter how high they are on the case. If you have just one fan on top let it suck air out again it works best this way because heat rises. If you have more that one fan on top of the case make it to where the on closest to the cpu is blowing out. And the one farthest blowing air in. I hoped this helped this is how I keep all of my computers running below 35c at load even with air cooled cpus

 

[kokin]

Thanks for the replies! I will try using 2 of same fans together.

 

[kokin]

Best answer selected by kokin.

 

[twistedspark]

Yeah of course it matters, here's what I always try to tell people building computers that involves 3 or more fans. Always keep the lower one(s) pulling air that way the cool air will rise thru. For the rear fan(s) always keep them blowing how air out because heat rises they will be most effective that way. If you have front fan(s) keep them sucking air in no matter how high they are on the case. If you have just one fan on top let it suck air out again it works best this way because heat rises. If you have more that one fan on top of the case make it to where the on closest to the cpu is blowing out. And the one farthest blowing air in. I hoped this helped this is how I keep all of my computers running below 35c at load even with air cooled cpus

I'd alway setup my fans the way you described above, but recently I added Asus PC Probe 2 and displayed all the available temp readings whilst trying every possible fan configuration and direction. My case is a Cosmos S with a 360mm open top. I found an 11ºC drop in the NB and 3ºC drop in the CPU when I turned the upper rear exhaust around and made it an intake!
Worth noting is my MB is the Rampage 2 Extreme which has a heatpipe from the SB, NB, and HD audio chips run to 2 heatsinks in the upper rear.

Now I've got a 120mm intake on the rear, 200mm intake on the side, 120mm intake on the bottom (blowing straight up), 120mm intake on the lower front (blowing in across the HDD cage), and an open top! This gives me the lowest temp readings I've ever had with my i7.

 

[kokin]

Yeah of course it matters, here's what I always try to tell people building computers that involves 3 or more fans. Always keep the lower one(s) pulling air that way the cool air will rise thru. For the rear fan(s) always keep them blowing how air out because heat rises they will be most effective that way. If you have front fan(s) keep them sucking air in no matter how high they are on the case. If you have just one fan on top let it suck air out again it works best this way because heat rises. If you have more that one fan on top of the case make it to where the on closest to the cpu is blowing out. And the one farthest blowing air in. I hoped this helped this is how I keep all of my computers running below 35c at load even with air cooled cpus

I think you didn't understand my question, as I was asking about Push/pull strength with the HS, not about the whole case.

 

[alhanelem]

nice pic kokin, anyway having two identical fans for push/pull strength is best.
also having the push fan blow air towards the rear is good too.

 

[kokin]

nice pic kokin, anyway having two identical fans for push/pull strength is best.
also having the push fan blow air towards the rear is good too.

Thanks! I was just wondering about having different fans vs identical fans and they do push air towards the rear. However, I do have a 200mm fan on top, but my SM2 isn't designed to blow bottom up, but front to back.