Hey unhappy ,

Terribly sorry mate, I completely misunderstood you.............I thought that it was your CPU not your graphics chip!

Yes, I guess that you are looking at adhesive rather than thermal compound.

I would certainly try acetone, and methylated spirits, and lighter fluid (petrol). Automobile brake cleaning fluid can work (please be careful, it contains benzine).

After that, a heavy duty paint stripper such as Nitromors might work. Sorry, I don't know what country you are in, so I cannot suggest brand names.

You might get a better result if you very gently rub the surface with a fine glass paper first. This will break any "heat seal" that may have formed and allow solvents to penetrate.

Basically, I would attack it with whatever comes to hand until I found one that works

Your biggest problem would be if it is an epoxy resin based adhesive?

I know that Arctic Silver make a removal fluid, but I have never used it, so I don't know what it is or how well it works.

The secret is to only apply a very small amount of fluid until you find one that works

You might try contacting the video card manufacturer?