Yeah, I've seen people say that many times in situations like this over the years.as5 is electrocapacitive, not conductive, still could be a problem, I would use a normal paste like Prolimatech PK1, MX-2, MX-4, etc. which are not electroconductive or electrocapacitive.
It's probably not a problem. The issue I think is that the die of that card is too large, so if you used cpu spread methods (small dot), it won't work well. Since you're gonna have to use more paste, the risk for overflow goes up, and you should probably get something that is safer to use.
Is it possible you trashed your 4870x2 due to the process and not the paste itself? People have been doing AC5 on them for years. I've never heard of anyone having an issue.Yeah and from personal experience I trashed a 4870X2 doing that once.
Have at it.
*shrug*