Some folks are still a bit nervous when it comes to installing a heatsink to a Thunderbird. So if you fall into this category, then it's time to shoot on over to OC Atlanta and see their take on the Purple Anodized AMD Shim that is made by HighSpeed PC. here's a snip:

"I've heard shims called many things from worthless to overpriced but one word I read recently seemed to make the most sense. Insurance. Just like insurance this shim offers no assurances you won't still crush your core but if you do, I think you should stay away from Las Vegas and Atlantic City because the odds are definitely not with you. It can be done I'm sure but it isn't easy."