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

546 Inspiron · 24 Mar 2010

Dwarf said:

The fan mounted on top of a heatsink should be blowing downwards onto it. You need the maximum air flow across the fins, and the only way is by positive air pressure. Indeed, if you have a case with a duct over the CPU/HSF assembly, it is not there to allow the warm air generated to exhaust the case - rather it is there so that the fan can pull cool room temperature air INTO the case and across the heatsink.

Try this (you will need an electric fan). With this analogy, the fan obviously represents the fan; your fingers the heatsink; and your body temperature the heat generated by the CPU. With the fan operating, stick both index fingers into some cold water. Hold them, one in front and one behind the fan at equidistant distances. Which finger feels colder? It should be the one that you held up in front, i.e. the one under positive air pressure.

Your anology doesn't hold any water because there is no shrouding. A shrouded fan would PULL cool air from the bottom and through the fins and expell it at the top where the case fan would pick it up (and out). And your fingers aren't in your computer case.

546 Inspiron · 24 Mar 2010

cloud8521 said:

CarlTR6 said:

Thanks for sharing your results.

no problem, sorry i could not get pictures, when im tired im sometimes crazy

Thanks for the work and interest. I don't want you to test anymore but was there a shroud? It's all about the shroud.

Phone Man · 24 Mar 2010

Fascinating thread. I got curious so I opened my case and looked at my AMD CPU heat sink and the fan is blowing down toward the CPU. I then pulled a few copies of CPU and MaximumPC magazines and looked at the adds and pictures. In every case the fans were blowing toward the CPU or GPU on video cards. All the adds for after market HSF were setup the same way. So I have to believe that the manufactures have determined that blowing toward the chip is the best. It has been a good discussion and a lot better then "Which AV is Best????" Some disagreement but no one got shot

Jim

cloud8521 · 25 Mar 2010

546 Inspiron said:

cloud8521 said:

CarlTR6 said:

Thanks for sharing your results.

no problem, sorry i could not get pictures, when im tired im sometimes crazy

Thanks for the work and interest. I don't want you to test anymore but was there a shroud? It's all about the shroud.

shrouds seems to be more problematic then helpful.

Kipper · 25 Mar 2010

Wow, what a fun thread.

So, with a little different setup, the SilverStone FT02 chassis which has a 90 degree rotated motherboard placement and running aftermarket air cooling (CM Hyper212Plus) which cannot blow or suck air onto the CPU or away from the CPU I decided to mount dual 120mm fans one each side of the sink. One blowing and one sucking. I figure I have to have the right answer with this setup.

You guys are a blast, seriously a great thread.

YTBOY83 · 25 Mar 2010

Kipper said:

Wow, what a fun thread.

So, with a little different setup, the SilverStone FT02 chassis which has a 90 degree rotated motherboard placement and running aftermarket air cooling (CM Hyper212Plus) which cannot blow or suck air onto the CPU or away from the CPU I decided to mount dual 120mm fans one each side of the sink. One blowing and one sucking. I figure I have to have the right answer with this setup.

You guys are a blast, seriously a great thread.

Hey i like that idea, do you have a good exhaust fan at the back.????

YTBOY83 · 25 Mar 2010

Have a look here http://www.tomshardware.co.uk/forum/170530-11-direction

CarlTR6 · 25 Mar 2010

Phone Man said:

It has been a good discussion and a lot better then "Which AV is Best????" Some disagreement but no one got shot

Jim

rmw020 said:

Have a look here http://www.tomshardware.co.uk/forum/170530-11-direction

Interesting; but not nearly as spirited as our discussion here!

YTBOY83 · 25 Mar 2010

I agree, i never knew that my thread would have so much response. I hope it is alive for a good few years yet.

Kipper · 25 Mar 2010

rmw020 said:

Kipper said:

Wow, what a fun thread.

So, with a little different setup, the SilverStone FT02 chassis which has a 90 degree rotated motherboard placement and running aftermarket air cooling (CM Hyper212Plus) which cannot blow or suck air onto the CPU or away from the CPU I decided to mount dual 120mm fans one each side of the sink. One blowing and one sucking. I figure I have to have the right answer with this setup.

You guys are a blast, seriously a great thread.

Hey i like that idea, do you have a good exhaust fan at the back.????

The 90 degree rotating of the MB and the "positive air pressure" of this chassis is quite unique. All intake fans (3X180mm) are bottom mounted with one 120mm exhaust fan on the top of the case.

I wrote a review of this chassis for SilverStone which you can read here:

The SilverStone FT02 Case: