I just finished a build using a Power Color 7870 Myst edition (Tahiti LE). After a hour or so of gaming I downloaded MSI afterburner and started seeing temps reach 90-91c steadily while gaming. First temp reading was during crysis 3 which is a pretty demanding game so I tried some stuff a little less graphically demanding and still hovering around 85- 90c. It idles at 34c-35c so more than a 55 degree jump seems like allot to me but I far from an expert. Aside from being nervous it's going to fry itself or put unnecessary heat into the case, the high temps cause the fan to run at 100% which gets to be quite annoying after a while. I was just curious because I read a benchmark where they OC'd the same GPU quite high (I'm running stock for obvious reasons for now) and was running at 65c and the fan never got over 60%. Only had it out of box 3 days and no dust built up.