CPU Fan Direction?

[thenderson]

Get some programs that watch the temperatures on various items in your pc and do a bechmark with it blowing in ans sucking out. My processor already has a fan sucking it. However my drives get hot so I got the drive monitor to see which direction is the most effective.
The reason I say this is everyone has diff ideas and you might as well see what works properly for you.

 

[saaiello]

Air should be blown down onto the heat sink this process also cools everything else around it including northbridge ram and the most important the VRMs. Pulling it threw could result in the motherboard overheating. Now maybe the CPU might be better cooled with it pulling up but that fan is not just for the CPU like i said its for the motherboard too.

Now since this post is so old tower heatsinks weren't popular then with a tower heatsink it still works best with the fan blowing threw the fins and pushing it to the exhaust fan. But what a lot of people don't realize is that those tower fans do nothing for the motherboard so good case cooling is essential and all high end motherboards come with big heat sinks on the VRMs and Northbridge to take more advantage of the air flowing around the case.

 

[randomkid]

This is interesting... a 4 year old thread resurrected but still is useful albeit with the changes in technology.

I myself set the fans to push the air thru the heatsink. The push is more directional as it makes sure the air is passing thru all the fins and going straight thru. If the fan is set to pull, then a good change the pulled air will come from the sides and not thru the heatsink as it will choose the path of least resistance... By passing thru the sides, it will not effectively pull away all the heat in the heatsink.

 

[planes]

Well I think Cooler Master has put the push air theory to bed. The 212 neither sucks or blows. All pun intended. It does a sort of side swipe over the fins towards the back of the case. But then, they have a whole different theory of cooling as they direct contact the cooling pipes to the cpu by cutting them through the sink.

 

[Beaker_GJ]

What is missing from this thread is empirical evidence. No one says I tested my CPU temp with the fan blowing this or that direction.

Yes, this thread is several years old, but it's still a relevant topic until a processor is designed which does not need external cooling.

When I first came to this thread I suspected the fan should be blowing away from the processor to draw the heat up the sink. After reading I can see how this would limit the air inflow to just around the edges of the sink and not in the center. Blowing air toward the center will create more airflow over the entire sink, which is the ultimate goal.

One thing aside that I can tell you from personal experience is that I work on a lot of customer's PCs and they get very dirty inside. The fan is going to draw dust into the sink, it's inevitable. I've seen it time and time again, the dust collects at the point the air first touches the sink. The question is, do you want the dust collecting near the processor because the fan is blowing away from it, or do you want the dust further away from the processor because the fan is blowing toward it. Personally, I would rather have the dust collect as far away from the processor as possible and allow the dust free fins to draw heat away from the processor. Yes, I know we should all clean our computers regularly and get the dust out, but for the average joe who never cracks the case open and has years of dust collecting inside the clear advantage is to have the fan blowing toward the processor.

 

[estebanrey]

OK here's a curve ball, what about if I use this CPU coolers

http://www.overclockers.co.uk/showproduct.php?prodid=HS-005-PL&groupid=701&catid=57&subcat=1395

(Prolimatech Megahalems Rev B CPU Cooler)

...and put two fans on it (which it allows), the one nearest the back pulling air and the on on the other side pushing air through...

Best of both worlds?

 

[snowonweb]

lol. my artic circle x64 cooler blows air into the fins then air goes out exhouse fan on the back. top fan blows air also. Front has fan in and now I will install side fan blowing air in and also i have Video card blowing air down onto the PSU that sits on bottom of case installed upside down blowing its air into graphic card. So now I am ready to install side fan that will blow air IN and wh IN. because when you want to cool down you put fan to blow into your face not air away from your face. The only reason you put fan away from your face is when you smoke inside the room and want smoke out, so that fan should blow lots of air right into my mobo. vga and it will be great.
LOL if pulling air out is better why don't they have air conditioners in the car that blow air out of the car instead on your face. I mean create some suction in the car ROFL. :lol:

 

[rtownsend]

Hmmm.

My friend has an HP Pavilion Elite m9250f (has Q6700). I was doing some maintenance (wouldn't boot, video card fried, replaced it), and decided to check the temps. 70C idle, 86C running Prime95. Problem. Took off the fan, and sitting on top of the heat sink was so much dust you could hardly see the heat sink. Took off the heat sink, cleaned, reseated with AS5, now 40C/70C (what I was expecting).

The heatsink fins did not look aerodynamically designed for inflow - it had hard square edges (which seems like it would encourage dust buildup). Which lead me to think about this question and wind up here.

I think a HSF could intentionally be designed for outflow, not inflow. And I'm wondering if that's what I was dealing with. Directly above the HSF, in the side of the case, it's perforated. Is this to get hot air out of the system, or to get cool air into the system and over the processor (and blow warm air over everything else)?

The dust buildup, non-aerodynamic nature of the top of the heatsink, and case perforations lead me to suspect this may have been an outflow design.

If anyone can definitively answer this, I'd appreciate it.

 

[Guest]

Think of it like this. If you was was all hot from doing work outside and you came in to get out of the heat and wanted some air. Would you put the fan in front of you blowing air onto you or would you turn the fan around and have it suck air around you? Makes common since that you would want the fan blowing ON you. Common guys use your heads.

 

[rtownsend]

I think I'll think of it like this.

I suspect HP took a stock heat sink, then lopped off the top of it because it was too tall, because the case was on the thin side. That left the sharp edges which gather dust so easily. So it's probably an inflow design with a kludge. But I'm just guessing. Hi HP

Again, if someone can definitively answer this, I'd appreciate it.

P.S. I could design an outflow cooling system, if I wanted to. And it would make sense in some ways (ie, getting heat out of the case as quickly as possible). So, those who are crapping on the question, and insisting that there's only one answer, aren't really helpful.

 

[coffee_holic]

@snowonweb & that other anonymous guy who isn't rtownsend:

The reason A/C units blow air towards us is because we FEEL the cool air on our skin and that makes us more comfortable. It doesn't actually do all that much to relieve our body of heat.

@rtownsend: Hope someone can

Hope someone can help you with your problem. =o


Beaker_GJ had a good point regarding where dust collects when fans blow or suck, but in the end, I'm going to have to go with sucking air, because it performs roughly along the same lines as exhaust fans for a PC as a whole: move hot air away, and fresh, cooler air will come in to replace it. If you have decent airflow in your case, the hot air will be whisked out the exhaust fans.

Of course, this is all moot to me, because I prefer heatsinks on CPUs. Makes more sense to me, especially with the aforementioned decent airflow and exhaust fans.

 

[cmt-alex]

Well, if you would be an engineer you would probably check a cooling fan spec and find that it does not like overheat! Just imaging a fan always sucking hot air from a heat-sink and heating itself. Fan's operating temperature raising above the spec, it works in stressed condition. What happens to its lubricant?.. So, you have to replace a cooling fan twice a year wondering why does not it work its 20-30k hours according to the spec...
IMHO, the only reliable way to install the fan with the air flowing towards a heat-sink.

 

[zjim]

For CPU Heatsinks with the older style fans, the air is supposed to be blowing down onto the CPU. That is why on PCs having a side intake air duct, the shape of the duct is small to large, with the large end directly over the CPU. This shape (small to large diameter) is known as a Venturi effect. It creates a cooling effect as the air moves from the smaller end to the larger opening. Besides, go to Intel's sight (or AMD's) and read the installation guide. Come on folks!

 

[Mousemonkey]

This topic has been closed by Mousemonkey