Thermal paste questions

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Originally posted by Murf
I agree with DrMDJ with a fan above the PS (I use this concept)athough ski's config is also a good one and inline with an Example from the AMD site;


http://members.cox.net/joemurphy/cooling.gif

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I just don't want somthing like THIS to happen....

http://keepernsol.com/RyanHomes/ryan...s/Ryan_p22.jpg

So This is how I'm going to do my case, the front lower fan will be Intake.(filtered)

the back Top Case fan will be INTAKE(filtered)

the back Bottom case fan Will be Exhaust, and the power supply(bottom intake)(middle) exhaust, sounds okay?

So basically My system looks like that picture, except I got a tall tower, so there is room above the power suppy, and it has a case fan just above the power supply.

or Do I need the bottom rear to be a Intake and the top rear as exhaust?:confused:

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Originally posted by SuperSparks
The idea of the thermal paste is simply to fill in the microscopic imperfections in the mating faces of the heatsink and processor die, so it should be as thin as possible. No thicker than a sheet of paper for sure. These instructions are useful:

Arctic Silver Instructions

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But wouldn't the excess paste just Sqeeze out?

Nope, but it might crack the motherboard. It's happened before.

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But wouldn't the excess paste just Sqeeze out?

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Yes,,but if it 'squeezes out' onto the CPU bridges,you can be in deep trouble...:(

And,, imo,,the most reliable airflow thru' a case is as descibed in the schematic given above: Intake low in front, exhaust high in rear. Intake in front and intake in rear=hot vortex in my experiences...:rolleyes:

As said above the purpose of the paste is to fill voids, imperfections between/in the mating surfaces of the cpu slug and the heatsink. The concept is that the paste is a better thermal conductor than air, so you want the paste to replace the air gaps that would otherwise exist in the voids/imperfections. However, paste inhibits thermal conduction (acts as in insulator) when it exists in places where the metal surfaces of the slug and heatsink could otherwise meet properly. So you don't waste (or want as little as possible) in these areas. The "ideal" would be to have paste only in gaps and none where good metal-metal contact can be made.

Paste will melt and flow under heat conditions (and part of its eventual effectiveness is dependent on this), but only to an extent. So if you have a lot of excess it will not all flow or be forced out (by the pressure between the heatsink and slug). Instead you end up with a buildup, contributing to the insulation effect described above.

Okay, since no one seems to believe me, I flipped my rear fan around to check the difference.

Blowing in: 41°C
Blowing out: 45°C

Maybe my case is a freak, but I'm sure not. I don't just make this stuff up, ya know :p

Tons of good advice here... thanks everyone :)

Ok, I understand how much thermal paste I need. I did in fact put too much on. I'll be taking it apart and trying it again shortly. And I'll be sure to warm up the paste before I try to work with it. Also, I'm asking for a gift-certificate to this computer shop I go to for Christmas. Hopefully Santa will put it in my stocking and I can get a fan for my video card.

And while I'm talking about video cards.... Fans for video cards work the same as the CPU fans, right? They blow air *onto* the chip, right?

Thanks for the link Abhoth. Almost all of those are well within my price range :)

As of yet, I don't have any air filters on my system. I've always prefered having as few restrictions as possible for the airflow and just clean out my system every so often. I have never had much of a problem with dust anyway. But now with these scrubbies being so popular I might invest in some.

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Originally posted by Parallax
They blow air *onto* the chip, right?

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Yup. It would probably work either way, but that's the most effective. It pushes the most through the heatsink.

And I can tell you of a 4c temp jump on my wife's system when I switched the rear fan to intake. Changed it back.
It really depends upon the case... the case makes a huge difference. There is the 'rule of thumb' that I follow... but experimenting with your particular case and such is permitted... ;-)

Something to note... When dealing with temperature differences such as was mentioned above and within the range being dealt with the difference is not really meaningfull. The values are already well within a perfectly acceptable range of operation and as such no greater stability or meaningfull extension of the processor life is going to be had. The benefits of cooling are subject to diminishing returns. Often times these days money and effort is put in to reducing temperatures beyond a point where there's really anything to be gained short or long term.

I figure as long as you are below 60C, why worry about it. 67C and above, now I get busy real quick.

Yeah, you start pushing 60c or beyond and it's time to rethink something!
Was more a commentary on fan placement and efficiency than temperature. Temp differences are simply noted as a barometer of that efficiency.