your silver thermal paste may not contain silver!!
taken from overclockers.com
might be old news to you, but its an important bit of info for all people at this site to hear
http://www.overclockers.com/articles938/if you use CompUSA thermal paste (shame on you

) or OCZ brand thermal paste then you might not have any silver in there!!
OCZ is doing a recall of its silver paste after it found out the manufacturer had not been making it to specification of at least 30% silver
compusa does nothing and prolly has not acknowledged the fact it has no silver in it...