CPU

Interesting conversation... Considering that all Intel, AMD, and 95% of the aftermarket guys all move air toward the heat sink, you gotta wonder why anyone would consider it wrong, or at least, inefficient.The objective is to cool the cooler! (hestsink)

Many years ago I had read a post on XtremeSystems by a guy claiming flipping the fan to draw instead of push would yield a better result. At that time I tested it myself with a few different coolers, and it always hurt me 5 to 10 degrees.

So from my perspective, I follow the manufactures on this.

Well, thanks for all the input guys. Appreciated.

Most, if not all of the fans mounted on heat sinks have the air blowing on the heat sink.

And, for people who have a chassis that supports a side case fan, having the CPU fan blow away from the heat sink would pose unnecessary turbulence from the air coming in from the side case fan--resulting in overall poor case cooling.

seekermeister said:

Product FRED said:

seekermeister said:

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.

I don't mean to demean your friend in any fashion, but the job description given does not make it clear that he is an expert on all things computer wise. I have no doubt that he is quite knowledgeable in the things that he deals with directly, but what you are reporting is what would be called heresay in court. This may not be a court, but it is still a place in which validity does come into question.

Oh please. Listen, I know you don't mean to judge or anything, and I don't expect you to believe me when I say this, but he is an expert on these things. Besides, just look at the laws of physics, specifically a vacuum. Overall, the system will be cooler if you just suck the air out from every fan. Why would you have two conflicting fans (rear and CPU)? This thread is over anyways, he'll try it out and we'll see.

mpcrsc562 said:

Most, if not all of the fans mounted on heat sinks have the air blowing on the heat sink.

And, for people who have a chassis that supports a side case fan, having the CPU fan blow away from the heat sink would pose unnecessary turbulence from the air coming in from the side case fan--resulting in overall poor case cooling.

As I stated before, a side fan should suck air out, not push it in.

Product FRED said:

Oh please. Listen, I know you don't mean to judge or anything, and I don't expect you to believe me when I say this, but he is an expert on these things. Besides, just look at the laws of physics, specifically a vacuum. Overall, the system will be cooler if you just suck the air out from every fan. Why would you have two conflicting fans (rear and CPU)? This thread is over anyways, he'll try it out and we'll see.

A rear out-blowing case fan and a heatsink-blowing fan are not conflicting. If anything, the rear case fan would help draw in cool air from the front--and over the cpu fan to aid in cooling the heatsink.

[QUOTE=CommonTater;643602]

CarlTR6 said:

rmw020 said:

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.

It's about the way air moves... If you stand behind a fan you don't actually feel the air motion, because 90% of it occurs very close to the fan in a very disorganized way as local air pours in to fill the vaccuum behind the blades.

This same air becomes the air stream you feel from a goodly distance in front of a fan. You feel it, because it's organized... it penetrates and travels.

This is what they call the Bernouli effect... moving air gathers more moving air along with it. The problem is that Bernouli's effect only works with pressure, not decompression of air (or fluids). The blowing on the palm example is one simple demonstration another is to bundle a garbage bag and blow it up like a baloon... it's going to take a lot of huffing and puffing to blow it up. But if you hold the end open and simply blow into the bag, you can inflate it with one good blast of breath. Because the air you blow into the bag gathers other air with it and causes a momentary pressure burst.

This relates to fans in that the front of the fan (which normally faces the heatsink, blowing air into it) creates pressure inside the fins, forcing air deeply into the blades getting far more heat conduction, whereas reversing the fan counts on a vaccuum to cause an air inrush which is mostly going to happen immediately behind the fan, with little or no penetration into the fins themselves. It will simply take the path of least resistance to fill the small pocket of reduced pressure right near the blades.

An odd confirmation of this is that a fan will spin faster when drawing air off a heatsink than when blowing air in... because the Bernouli effect causes pressure when causes resistance against the fan blades... and it's that pressure that drives cool air across the entire fin surface of the heatsink.

WHEW... does that help?

So basically, exhaust.

Side fan should blow in and the top fan (if you have them) should blow out.

Look at the Cooler Master HAF series... One front intake fan, one side intake fan, one rear exhaust, and one top exhaust.

I think Cooler Master and other case makers have some knowledge in what they're doing.

I think Intel and AMD certainly have more...