Question regarding thermal paste

cubix

I am running a Amd-Xp2000 cpu at the moment with out any thermal paste with a Zalman cooler http://www.zalman.co.kr/english/product/cnps6000Cu.htm
At the moment the cpu temp when idle is normally 52-55C,does using the thermal paste make a big difference
Thanks

PrecariousNuts

Around 2C of a difference I think

SouperComputer

55deg while not baking, is a little much for idle.

you should be generally aiming for 40-45 idle or lower. When you say no paste, do you mean you've used what is on the base as standard, or there is nothing between the HS & DIE?

elexes

the temps ur gettin aint to bad . but use paist should be used

cubix

I just stuck the HS on top of the Xp chip(no paste)

astrofool

was there even a thermal pad (little pink square).

If there isn't, you've installed the heat sink wrong, they really need some sort of transfer medium. The heatsink should come with some paste or a pad at the least.

Inspector Gadget

It's a very bad idea not to use some sort of thermal transfer substance on your CPU.

Although a lot of people think otherwise, thermal paste is (in general) actually a poorer conductor of heat than the heatsink is. Aluminium, copper, silver and gold (in that order) are amongst the best thermal conductors known (that aren't ridiculously expensive to obtain/produce, at least).

(This is why a lot of the higher performance compounds use compounds/amalgams of these metals - the Arctic Silver family is a good example. Of course, these metallic pastes conduct electricity, and as such should be applied with great care to avoid shorting anything out.)

What it does achieve, however, is to make sure that the largest possible area of CPU die is put in contact with the largest possible area of heatsink.

This is important because neither the base of the heatsink or the top of the CPU die are perfectly smooth. The heatsink will have (at best) striations (shallow grooves) from the milling/polishing processes, it may also have casting errors, such as dimples or raised dots from splashes and/or impurities. The CPU on the other hand, while reasonably smooth, tends to have a lot of (indented) lettering on it, and may also have small manufacturing defects of its own that preclude the surface from being smooth.

While lapping the heatsink (smoothing the base of the sink with very fine, usually wet/dry sandpaper) can help, it doesn't cover everything. Thermal paste (as well as the phase change thermal pads) get into all of the nooks and crannies in both surfaces, and tend to improve the transfer of heat from CPU to heatsink accordingly. It also helps when the CPU isn't exactly parallel to the top of the die (which can easily happen)

The only important thing to remember with this sort of thing is that the quantity of paste that should be used is tiny; it should be squeezed out of those areas of the surface that don't need it.

Hope this helps,
Gadget

cubix

Thanks lads for all the input