I've had good success using acetone, but exercise care since it attacks enamels and plastics.

I used strong alcohol. Just let the alcohol sit on the left over glue and it will soften.

Use a heatgun to soften it up, then clean it with a dry q-tip. Whatever remains, clean with charcoal fluid.

Non-organical solvent + cotton cloth, use it a bit don't let it leak from cloth

I would heat it up with a hair dryer (poor man's heatgun) and then attack it with a guitar pick, credit card, or other plastic implement. If 99% isopropyl alcohol doesn't doesn't soften the glue up sufficiently, some amount of scraping / chipping is going to be needed. The trick will be not to damage the heat spreaders.

You could always sand it off. You may want to lap the chips, anyway to improve the heatsink/gpu mating surface, later.

maximus wrote:

I would heat it up with a hair dryer (poor man's heatgun) and then attack it with a guitar pick, credit card, or other plastic implement. If 99% isopropyl alcohol doesn't doesn't soften the glue up sufficiently, some amount of scraping / chipping is going to be needed. The trick will be not to damage the heat spreaders.

You can youse this method, is just one of the best, but in other order, like: first 99% isopropyl alcohol and then go up with a hair dryer (poor man's heatgun). It should help 😏