Frag tape

aka Thermally Conducting Adhesive Tape... what is the "best" one i.e. best heat conducting ability or are they all the same, and where can I get some in the UK? Local Maplins, B&Q, Electrical stores have nothing!

Is there a reason why you have to use tape? The common argument would be to go with your typical heatsink compound.

Yes, I want to attach some BGA ramsinks to my graphics card memory chips but don't want to use epoxy (invalidates the warranty!) - there's no other way to mount them that I can tell

Well... I would probably juse use whatever tape you have. GPU Ram ICs don't put off so much heat as to warrant super-conductive thermal interface tape. You could use the best thermal tape out there and probably only see a 1° difference compared to the average run-of-the-mill tape. Just buy from a trusted site and you'll probably get a good product.

I think that normal double sided tape can act like a pretty good insulator. I would not go with normal tape if you already purchased (expensive) ramsinks... kind of defeats the purpose of getting that small cooling benefit.