Fan Direction - Push air onto the coller or pull air from the cooler?

Supertaff · 13 Jan 2008 at 12:44

As it says in the title which way round should the air flow be for cooling, should it push air from the case onto the cooler or oull air away from the cooler?

Cheers

Taff

Gackt · 13 Jan 2008 at 12:48

From personal experience it's always been, for me:

Cool air into case -> heat away from CPU cooler -> Out of case

Sone · 13 Jan 2008 at 13:06

the suck or blow argument is as old was when fans first started appearing on CPU's.

Depends on the cooler but normally i think blowing is better

mame · 13 Jan 2008 at 13:16

i have: front fan blowing into the case via a dust filter. side fan blowing out of the case which sits just above the graphics card and the big case fan at the back blowing out of the case.

rubberduck · 13 Jan 2008 at 17:28

Try both and see what your temps are like!

pegasus1 · 14 Jan 2008 at 10:18

rubberduck · 14 Jan 2008 at 10:28

I think there are 2 sides to the argument. I've no doubt that blowing would provide better cooling to a heat sink in an open environment.... You always blow on hot soup to cool it down right? However in the enclosed environment of a case where maintaing a flow of air through the case is important (In at the front, out at the back) sucking may be more beneficial as it will keep case temps lower.

slowrunner · 14 Jan 2008 at 11:11

I'd say the ideal way would be case fan at front pulling in, cpu fan blowing front to rear, with case exhaust fan behind that.

Wizardskills · 14 Jan 2008 at 11:57

LOL @ this threads innuendo's

On a serious note though...pushing air over the heat sink will allow more heat to be transferred, but at the cost of it not getting out the case as quick. Pulling air over the heat sink has the opposite effect, i.e. less heat transfer but quicker exit.

The best solution is to use both; however it will be quite loud.

rubberduck · 14 Jan 2008 at 12:03

Wizardskills said:
LOL @ this threads innuendo's

On a serious note though...pushing air over the heat sink will allow more heat to be transferred, but at the cost of it not getting out the case as quick. Pulling air over the heat sink has the opposite effect, i.e. less heat transfer but quicker exit.

The best solution is to use both; however it will be quite loud.

I agree.... I think having a stream of air impinging on a heat sink creates much more noise than if it were sucking away from the heatsink... This means that the 'suck configuration' allows for a fan that can push more air through the case while still keeping noise levels down.

pegasus1 · 14 Jan 2008 at 12:12

To be honest there is only one side to the story and for those that disagree please try it. A fan blowing air over the HS will produce cooler temps than if trying to suck warm air up from the HS.
Case cooling is a different kettle of fish though but generaly cool air coming in low down at the front and warm air going out high up at the back.

There are many variations on this theme and believe me i have tried loads. My current system is housed in a large Chieftech Dragon server case and uses negative pressure to aid cooling. 120mm fans expel air out of the roof, back and top side panel causing air to be draged in through vents at the bottom.

I agree.... I think having a stream of air impinging on a heat sink creates much more noise than if it were sucking away from the heatsink... This means that the 'suck configuration' allows for a fan that can push more air through the case while still keeping noise levels down.

Try it but i know the outcome.

Topitoff · 14 Jan 2008 at 13:59

This has a very easy answer; Buy a Tuniq Tower, the fan is in the middle of the heatsink so it sucks over half of it and blows over the other half and it's one of the best air coolers available.

schumi84 · 14 Jan 2008 at 14:26

After just fitting my Tuniq, i have 2 80mm fans at the back sucking in, blowing over the cooler. Need to check the orientation of the cooler inside the Tuniq but noticed that when i turn the fans round at the back of the case, so drawing air from the cooler out the back of the case, my temps go up at least 6 degrees when under load (from 59 to 65 on 2 cores and 52 to 57 on the other 2 cores.

pegasus1 · 14 Jan 2008 at 14:33

When using air cooling, remember that the CPU fan can only cool with the air that is in the case, if the temp of this air rises then the fan is using warmer and warmer air to try and cool a hot component. The air inside will continue to rise in temperature unless it is exhasted. I have seen a 20C drop in CPU temps just by cutting a 120mm blow hole and attaching an exhaust fan. An easy way to see if your case is well vented is to remove the side panels, if this lowers the case/component temps then you need to improve your case cooling.

schumi84 · 14 Jan 2008 at 16:50

Have just checked on my fan and it also facing forward (so blowing air towards the front of the case.) Just remembered that i have a 120mm fan stuck to the floor of the case blowing forward as there is just about ample space to act as an exhaust out the front.

bledd · 14 Jan 2008 at 17:24

blowing should be better

when a fan is sucking, it would suck from the sides of the heatsink (where there's less resistance), when blowing, the air has to go deep into the heatsink as there's a sort of wave effect when it hits the motherboard, meaning it will go into the heatsink further, then 'blow' to the sides

think of it like this..

if you had a straw in your mouth, and held it above a table covered in glitter -say 3 inches above it, when sucking air in, it'd barely move the glitter, if you blew out however, all the glitter would spread to the sides

pegasus1 · 15 Jan 2008 at 08:56

bledd. said:
blowing should be better

think of it like this..

if you had a straw in your mouth, and held it above a table covered in glitter -say 3 inches above it, when sucking air in, it'd barely move the glitter, if you blew out however, all the glitter would spread to the sides

A most bizzare analogy but very true. :cool:

Supertaff · 15 Jan 2008 at 13:58

Ok, thanks for the time all of you have taken to reply to the question.

Currently I have a Thermalright Ultra-120 with a 120 Noctua fan puliing air from the HS, with a front fan dragging air in over my HD's and a back fan pushing air out of the case just by the side of the HS. I think I'll change that fan pushes air over the HS towards the back fan to be extracted from the system.

I'll temp test the before and after and post back any results to prove if it works or not.

Cheers

Taff

rubberduck · 15 Jan 2008 at 14:12

Supertaff said:
Ok, thanks for the time all of you have taken to reply to the question.

Currently I have a Thermalright Ultra-120 with a 120 Noctua fan puliing air from the HS, with a front fan dragging air in over my HD's and a back fan pushing air out of the case just by the side of the HS. I think I'll change that fan pushes air over the HS towards the back fan to be extracted from the system.

I'll temp test the before and after and post back any results to prove if it works or not.

Cheers

Taff

I will be interested in how much this lowers your temps by.

Bleek · 15 Jan 2008 at 15:24

Always have air PUSHED/BLOWN through a heatsink, much more effective that trying to pull air from around, in and then out. In this scenario sucking requires more force than blowing to fill the same surface area.

Ultimately a heatsink that has air pushed through to an external vent is best i.e. a rear case fan or psu fan.