thermal compound for my xp2700 retail???

0zzie

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Guys,
I picked up a xp2700 retail boxed ie with fan etc and its has some kind of thermal substance already on it (I have to peeel a sticker off to reveal it before applying the heatsink).
I have some thermal compund in a syringe thingy - should I also use that or are they not compatable??

Thanks
 

Stain

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That is a thermal pad. They offer the worst heat transfer so if you can remove it and use your "syringe thingy". Do not use both. When applying thermal paste only use a little, you only need a thin layer.
 

unoc

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No !!! You must use the thermal paste you have only if the thermal pad on heat sink is missed.
You may use a thermal paste only if you remove (i.e. using alcool) the thermal pad.
The theory which governs the heat transfer between the CPU die and the heat sink and then the ambient has been already exposed several time on this forum.
The CPU has, in some way, to disperse the heat it generates during operation. The power it can disperse is directly proportional to the difference between the CPU die temperature and the ambient temperature as well it is proportional to this difference by means of a coefficient which depends on the speed of air which lap the CPU. This last coefficient represent a resistances to the heat to be trnsfered to air. This resistance also is function of the ability of air to dissipate the heat. As an example, air has the lowest ability to dissipate heat, silver and copper has the best ability. The thermal paste or also the thermal pad are not so good as copper or silver but much better then air. The heat generated by the CPU is transferred to the heat sink through the thermal paste/pad which has the charge to avoid air to be enclosed between the CPU die and the heat sink.
Because the thermal paste/pad has a lower ability to transfer the heat with respect to copper, it is important to avoid a too thick layer of thermal compound between the CPU and the heat sink.
In this way the CPU will disperse the generated heat not through air but by means of the heat sink. The heat sink has an enormous heat exchanging surface with respect to the CPU die, resulting in a big reduction of the cpu temperature. Moreover the fan can increase the speed of the air lapping the cooler surface, even reducing the CPU temperature.
To have the lowest cpu temperature you should: use a copper heat sink, a good fan, use a good thermal paste (i.e. Arctic Silver 3), reduce the ambient temperature (cooling the case internal by air circulation).
The thermal paste (it is very soft) should be replaced ever 4÷6 months. The thermal pad generally does not need to be replaced, even if it has a little lower ability the transfer the heat.



______________________ <font color=red>A straight line never ends……………….until it comes up against a vicious circle</font color=red>
 

0zzie

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Unoc - thankyou for the substantial post.

I understand what you are saying about variables which determine cooling efficiency.

Im just not 100% clear on what you are recommending

I have a brand new CPU with the thermal pad fully intact.

I also have a tube of "Coolermaster Premium Thermal Compound "

what is best to do - thermal pad only or should I remove the thermal pad (you say with alcohol) and use the coolermaster compound instead. In either case - I ought not use both - is that right?

Thanks
 

Stain

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I probably should have been more clear. But being that you don't really know what your doing it might be easier(+safer) to just leave the thermal pad on and use that.

When I said it was the worst I wasn't including air or anything else no one would use to transfer heat from CPU to the heatsink.

If you don't plan to overclock then the pad will do fine. However using the paste will allow you to keep the CPU a few degrees cooler (varies depending on type of thermal compound and application). If you do think you need to use that paste then you need to remove the pad completely (yes alcohol works well). There should be no sign that the pad was ever there, needs to be shiny smooth clean. Then a thin layer of paste can be applied with just a drop and spread with a razor blade (or another means, just so its thin).
 

0zzie

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Thanks Stain

Im not planning to overclock now - but jeez 2 months ago I wouldnt have thought I would be building a PC from scratch - so never say never and all that.
I'll take on board all you guys have said.
It doesnt sound too dificult to apply the paste in the manner you described but last thing i wanna do is trash my CPU. Even if I dont overclock - the better the heatsink works, the slower I can run the fan (not sure if the fan that comes with the XP is variable even though my MOBO supports variation).

PS - if I just use the thermal pad for now - can I change it later - its not like an adhesive which is permanent is it?

Thanks again
 

ad_rach

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nothing is permanent.if u want to remove the pad later it should be easy enough with some alcohol or acetone.

no matter how hard you try, you can't polish a turd. :]
 

0zzie

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"nothing is permanent"
I get answers to my CPU questions and philosophy - love this board :).
Ad_rach thanks for that
 

unoc

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Ozzie, the problem is well clear, I believe that AMD says right when it writes the following:
Thermal pad is more stable and does not fades after a while. Thermal paste (just like Coolermaster premium or Arctic Silver 3) have better thermal performances, but after some months the user needs to replace and refill the thermal compound which may leave the "sandwitch" between the cooler and the CPU allowing air to enter the interface.
Consequently if you use to dismount frequently (every 2 or 3 months) the cpu cooler just to clean it from powder, then you will have better performances using thermal paste. If you do not plan to remove the cooler along some years, you need to use the thermal pad which is less efficient but is definitively more stable.
In any case you can use only one thermal compound. If you use the thermal pad, just leave it, if you want use the thermal paste, you must remove the thermal pad using some alcool. When you put the thermal paste on the die, you need to use a very small amount of paste (a "lentil" of paste is enough) just to cover with a thin film the die.

______________________ <font color=red>A straight line never ends……………….until it comes up against a vicious circle</font color=red>
 

0zzie

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Unoc - thankyou - thats perfectly clear
I understand the tradeoffs
Think ill stick with the pad unless or until I start overclocking or have heat issues.
Thankyou guys for the superb information