Should the case fans blow in or out?

Hello,

Ok, i need some recommendations here.

I have 5 fans in all in my computer. 2 in the front of the case, 1 rear, 1 top, and 1 side fan aiming directly at the CPU. ALL THE FANS ARE 80 MM.

I just need some one to tell me which to blow in and which to blow out.

Thanks.

 

The 2 in the front need to blow in so they blow air across the HD's to the back of the case.
1 at the rear blows air out of the case.

1 in top blows air out of the case and the side fan blows air into the case which aids the CPU fan and general M/B and cards cooling.

Like mine (except I only have one at the front) yours may be a bit noisy, but she sure won't overheat.

 

Im not really about noise. Omfact, i realy dont care how noisy it gets.

Anyways Thanks.

 

I think the side fan is meant to blow air out. it doesn't make sense for it to blow it in because then it hits the air blowing up from the HSF and blows it back onto the CPU. If it blows out, it takes the hot air away.

 

Front and side fans blows in as as should the fan on the HSF. Fans at rear. top and in the PS blows out.

 

As mentioned the side fan is there to aid the CPU fan and general motherboard cooling. So it blows IN. I'd like to use s*cks in but the BBS net nanny doesn't like that word.

 

My ATX case came with a side-mounted 80mm fan blowing in the general direction of the AMD Athlon XP 2000+ CPU which, of course, had its own cooling fan. The only other fan (other than a small one on the sub-processor) was the one in the power supply (PSU).

About 18 months ago, as part of a major upgrade of my system I installed an AMD Athlon XP 2400+, which ran hotter than the 2000+ previously installed. Because I was concerned about cooling, I installed a new heatsink and fan, a higher output PSU with two fans, and replaced the IDE and floppy drive ribbon cables with round cables.

In addition, I ran a series of tests with the side-mounted case fan 1) blowing in, 2) blowing out, and 3) removed from the case. Surprisingly, the highest internal temperatures were found when the side-mounted fan blew into the case. The lowest temperatures were achieved when I removed the side fan and installed it as an exhaust fan on the rear of the case (there were provisions for a rear fan, although one was not originally installed). My conclusion was that the side-mounted fan, whether blowing in or out, disrupted the airflow through the case, in particular the airflow around the CPU and its heatsink/cooling fan.

I subsequently discovered that AMD had published a "white paper" on case cooling which bore out my empirical observations. Even though it was published 4½ years ago, the information would still seem to be valid.

In short, dump the side-mounted fan (and, perhaps, the front mounted ones) in favor of one or more rear-mounted exhaust fans.

 

Hi Jim,
Whilst I agree that your theory may in fact be correct. In my case (pun not intended ) my internal temperature seems well within spec, so I'll leave the side fan blowing in for overall MB cooling with the fan on top of the case blowing out. But the 80mm fan I installed in front of my HD's has reduced the temperature of my SATA HD by a considerable amount. In my view this fan (apart from the CPU fan) is probably the most important fan in my enclosure. It also cools the IDE ATA 100 secondary drive, although heat build up is not as big a problem with IDE drives.

Cheers,

Pau

 

I just recently bought a case with a side mounted fan which blows out as installed by the factory. I think it is meant to exhaust the cpu heat as several cases I ran across while shopping had a horn arrangement with the side fan that had an approx. 3" tube extending from the side fan over to the vicinity of the H/S fan to be sure to capture the heat from the cpu. Seems a fair idea to me. Mine doesn't have the tube but some do. I might reverse it however to blow in since no tube. Or place it on the back to exhaust.

 

I have an exhaust fan and an 80mm fan in the back of my case. I've taped up the holes in the side and I have one of my drive bays in front open. This creates a nice flow from the front to the back of the case. If you put your hand over the bay you can feel it sucking in all that cool air. One reason I did that way was because i have this old school 2 drive bay tall scsi drive that gets warm and I wanted to make sure it was getting enough air since it was the general reason the temp in my case increased. It has made a difference. I also taped up any openings in the back (i.e. all those lovely pci slot covers I've lost)

 

all fans should bow into the case. Only the fan in the rear of the case should blow the hot air out. (hint) if the Computer is in a desk that block air flow the front fan should blow out.