View Poll Results: Should a CPU Fan be intake or exhuast?

CommonTater · 23 Mar 2010

seekermeister said:

I agree, everyone is entitled to their opinions, and they are entitled to express them, but I prefer to know and understand the nature of what a person says, whether it is simply opinion, or something more substantial.

Along the lines of personal opinion or perspective, I have been thinking about your vacuum fan arrangement. Obviously, what counts is the amount of heat that is imparted to the airstream, and since the majority of the heat is going to be at the base of the fins, nearest the CPU, it would seem that the amount of air that comes in cantact at that point would be a critical factor in cooling. Since the vacuum fan would be pulling air laterally along the full length of the fins, some of the airflow would never have contacted the base area. Plus there would be a point between these lateral flows, near the base, that would be either a dead zone or an eddy, which would not conduct heat as well as a fan blasting directly and evenly on it.

Hi guys, I think I might be able to settle this for you... There is good reason why cooling fans always blow air onto a heatsink instead of drawing it away...

It's as simple as this...

Moisten (lick?) the palm of your hand, hold it about 2 inches from your mouth... Now suck air in as hard as you can... Feel any cooling effect?

Ok, now repeat the procedure, moist palm, about 2 inches from your mouth... now blow out as gently as you can.... Feel that?

Blowing cool air onto a heatsink is rougly 10 times as effective as trying to draw the hot air off.

CarlTR6 · 23 Mar 2010

rmw020 said:

I have thought about this in depth, if my cpu fan is set as exhaust then there is not any cool air helping the cpu stay cool. If i have it set to intake then air is helping keep the cpu cool whilst still blowing heat back. Answer this, shall there be more cool air getting blown back than there is hot air.

I think the cpu need cool air.

What do you think??????????

I agree that the CPU needs cool air and I personally think the the fan vlowing toward the heatsink and CPU is the most efficient. However, even if the fan is exhausting - blowing away from the heat sink, cooler air is still being drawn across the heatsink and CPU. I just don't think doing so is as efficient.

seekermeister · 23 Mar 2010

rmw020 said:

Good points, i suppose it also depends on how you have your intake fans set up.

I shall try it when i wake up and take temp readings. Thanks.

This is what I had hoped that Product FRED had already done. At least if there is a difference, then it would give us something to go on, more than opinions. Let us know what you find out.

Product FRED · 23 Mar 2010

seekermeister said:

Either way, the air is cooler coming in, than going out. The crux is which direction is permitting the air to absorb more heat? The question is somewhat rhetorical, unless you have something to add that you haven't already said.

Like I said, I called for advice and was told what I expected. That exhaust is the way it's supposed to be. You create a low-pressure buffer zone when you use an exhaust system, drawing in the cool air as the hot air is fanned out.

seekermeister said:

rmw020 said:

Good points, i suppose it also depends on how you have your intake fans set up.

I shall try it when i wake up and take temp readings. Thanks.

This is what I had hoped that Product FRED had already done. At least if there is a difference, then it would give us something to go on, more than opinions. Let us know what you find out.

This is who I called: http://www.spoke.com/info/p6Jv6mt/AbeSuleiman

YTBOY83 · 23 Mar 2010

seekermeister, i have a nice side fan blowing air on to my gpu and and just above it to help keep my case under the cpu cool. If i set my cpu fan as exhaust, would that air be blown back by some of the air coming from my side fan.

Product FRED · 23 Mar 2010

rmw020 said:

seekermeister, i have a nice side fan blowing air on to my gpu and and just above it to help keep my case under the cpu cool. If i set my cpu fan as exhaust, would that air be blown back by some of the air coming from my side fan.

Read this: Side Case Fan Position - Exhaust or Intake? - Cooler-and-Heatsinks - Overclocking

seekermeister · 23 Mar 2010

Product FRED said:

This is who I called: http://www.spoke.com/info/p6Jv6mt/AbeSuleiman

You called?

Product FRED · 23 Mar 2010

seekermeister said:

Product FRED said:

This is who I called: http://www.spoke.com/info/p6Jv6mt/AbeSuleiman

You called?

Yes. Good friend of mine. He works in the city. The only mistake on that profile page is that on the top it should say he works at Ambac Assurance. It is corrected in the bio though.

seekermeister · 23 Mar 2010

Product FRED said:

rmw020 said:

seekermeister, i have a nice side fan blowing air on to my gpu and and just above it to help keep my case under the cpu cool. If i set my cpu fan as exhaust, would that air be blown back by some of the air coming from my side fan.

Read this: Side Case Fan Position - Exhaust or Intake? - Cooler-and-Heatsinks - Overclocking

Simply looking at the title of the link, it appears that it is speaking of the direction of the side fan, not the CPU fan.

Product FRED · 23 Mar 2010

seekermeister said:

Product FRED said:

rmw020 said:

seekermeister, i have a nice side fan blowing air on to my gpu and and just above it to help keep my case under the cpu cool. If i set my cpu fan as exhaust, would that air be blown back by some of the air coming from my side fan.

Read this: Side Case Fan Position - Exhaust or Intake? - Cooler-and-Heatsinks - Overclocking

Simply looking at the title of the link, it appears that it is speaking of the direction of the side fan, not the CPU fan.

Yes, because he was asking about the side fan as well. Now if you have a side fan sucking out air, you'd need the CPU fan to also suck out the air (exhaust), otherwise there would be two head-on air currents and heat would build up inside the computer.