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

[ccc10156]

It is the air molcules that must absorb the heat and take it away. Using a vacuum lowers the air pressure thus reducing the number of air molecules available for heat transfer. Blowing into the HS will increase the air pressure and thus produce more air molecules to transport heat away.
All stock CPU Fans are blowing down on the CPU, for a good reason.

Next, the airflow inside the case. If You use one fan for blowing fresh air into the cabinet, You will need two fans to pull the same amount of air out again, because the warm air is thinner and the fan therefore is less efficient.

If You blow air into the case from the front, make sure it does not blow at the graphics card. These card tends to blow air into the case, so if You place Your itake fan in front of Your Graphics card You will get a hotter GPU temp.
Everest Ultimate, when running displays temps on the taskline, so try moving Your fans around and watch the temps change in real time. This way I found that a fan placed on top of the graphics card (tower case) angled 45 degrees inward, lowered main board temp by as much as 9 degrees.

Just my 2 cents worth.

Best of luck

ChrisD

 

[Bleek]

Good point about case fans 'generally speaking' 1x 120mm intake will be sufficient to feed a rear 120mm AND the PSU's exhaust fan, so in affect a 1-in to 2-out ratio.

 

[pegasus1]

I have 3 x 120 blowing in and 6 x 120 (inc psu) sucking out in my Dragon tower case.

 

[Supertaff]

Hi Pegasus,

Do you have to wear earplugs when your next to your computer with that many fans?

Must be like being next to a dyson.

Taff

 

[Bleek]

I maintain an ambient case temp of ~22'C with just 1x120mm front, 1x120mm rear and 120mm on the PSU. Clearly the airflow through my case is good, but I just make sure cables are well tied and guided out of flow, I have 4x SATA HDD's and a heavily overclocked CPU and 'just' 2 fans cause me no temp control issues.

Why on earth would want/need more is questionable, especially 6x 120mm!

 

[Energize]

Hi Pegasus,

Do you have to wear earplugs when your next to your computer with that many fans?

Must be like being next to a dyson.

Taff

Not with a fan controller it won't be. The fans will only go as fast as they need to. I have an 92mm fan blowing in and a 120mm fan sucking out, and the noise is exactly the same as if they weren't even switched on.

 

[Scougar]

Just to add into this. Sucking air through fins is quieter than blowing through them.

Another thing to consider is that you ideally need AT LEAST an inch of cowling between the heatsink and the fan if sucking so that good distribution of air flow occurs. If you don't you will get dead zones (hot spots) on the heatsink. A lot of heatinks don't come with any cowling and are ineffiecient as a result

Mind you, my experience of this comes from setting up fans for car radiators.

Matthew

 

[rubberduck]

It is the air molcules that must absorb the heat and take it away. Using a vacuum lowers the air pressure thus reducing the number of air molecules available for heat transfer. Blowing into the HS will increase the air pressure and thus produce more air molecules to transport heat away.
All stock CPU Fans are blowing down on the CPU, for a good reason.

*Snip*

ChrisD

Won't increasing the pressure also increase the temperature?

 

[oggmonster]

Personally I use pull on my ultra 120 extreame. I got slightly better temps on my G0 q6600 @3.6ghz (admitidly only 1-3oc). Also looks like someone else had similar results as me. Again, this could just be exclusive to this cooler.

Push-Pull seems to be the best config, followed closely by Pull, and lastly by Push—altho the differences are surprisingly small.

http://forum.abit-usa.com/showthread.php?t=123901&page=2

 

[ccc10156]

Won't increasing the pressure also increase the temperature?

You are right, it will, but the temp increase is so small that it will have no impact. The increased airflow will more than make up for the extra temp which I will estimate to less than 2C.

Do You have a CPU temp monitor You can watch while utilizing Your CPU?

If You do and have room to spare, just try to reverse the CPU fan and watch the diff. in CPU Temp.

And.. Please don't forget to post Your findings. We may all be wiser

ChrisD

 

[bledd]

A most bizzare analogy but very true.

real world examples for the win

 

[pcoltrane]

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.

This isn't true. Most of the fan noise you hear is created by turbulence, and this is much more significant where the airflow is disturbed on the intake side than the exhaust.

Ideally you should always try and leave at least the fans width of open space on the fan intake side to minimise this turblence, ideally more.

As the intake side airflow is more sensitive to disruption, with a fan attached to a heatsink sucking air away from it, the resultant turbulence will probably mean a slight reduction in efficiency of the fan.

The ultimate result will be dependant on the overall airflow within the case, but I suspect that using the fan to suck from the heatsink will produce worse results and more noise for the majority of people.

If you've ever tried modelling case airflow in Floworks, its amazing what small differences to layout etc can do to temperatures (particularly eliminating hot spots around hard drives etc)

Marc

 

[pegasus1]

Hi Pegasus,

Do you have to wear earplugs when your next to your computer with that many fans?

Must be like being next to a dyson.

Taff

You cant hear them over my fridge. they are all at minimum speed on a fan controler. i have 4 x 120mm push/pull on my Swiftech Rad and 2 x 120mm push on my Black Ice Rad.

1 x cheapo 120mm fan at full speed is far far far noisier than 10 slow moving decent 120's.

 

[C64]

I thought Blow and suck were the same thing.

 

[Soul Rider]

I thought Blow and suck were the same thing.

WARNING TONE LEVEL ALARM!!!

TONE DROPPING TO CRITICAL STATUS!!!

 

[pegasus1]

I thought Blow and suck were the same thing.

You avin a laugh