<< I am new to this thermal compound stuff...
can anyone please explain THOROUGHLY what does it do?
And....do i have to use it with AMD cpu's.....??????
THX >>
The goal is to get heat out of the processor, into the heatsink and into the air. Due to the realities of nature and manufacturing, the heatsinks are rarely perfectly smooth. Placing a heatsink in a bare-metal contact with the CPU will still have pockets of air in the surface irregularities. Air doesn't transfer heat as well as metal, so we need something to fill up the air pockets and make a more thermally conductive connection.
Thermal compounds are typically some metal in a suspension of goo. Putting this between the CPU and heatsink helps improve the heat transfer. There's a bit of an art to it, too little and you may not get a good seal, too much and you may actually insulate instead of transfer. And as the discussion here goes, there's some disagreement as to which thermal compound is best.
Do you need it? With a Duron/Athlon, yes! The question really becomes what kind? The discussion here is about third-party grease. Retail processors which come with a heatsink will have some sticky goo already attached to the heatsink. In the past these were actually thermal tape, adhesive pads that purported to be thermally conductive. Many people claim they did more harm than good, and they were certainly right as processors got hotter. Nowadays that goo is a thermal phase-change compound which is fully endorsed and recommended by AMD. And in my own unscientific tests, it does about the same as most of the thermal grease out there. And the AMD warranty only covers the retail CPU WITH the HSF and goo it came with.
The two biggest downsides to the thermal phase-change goo is: 1. If you overclock, you are exceeding AMD's tested configuration, so there's no garauntee the goo will perform. 2. If you are swapping heatsinks regularaly because of testing, tinkering, whatever, then the thermal phase-change material has got to go, preferably before you use it. Once it's applied, it's like getting gum out.
Personally, I use Arctic Silver II. That's based solely on the popularity of the product.