Sorry to hear about your card. I run two in crossfire and I try to keep them both below 85C max, and below 80C if possible, by using an aggressive custom fan curve.
The thing that usually overheats on these cards are the VRMs. They will overheat before the actual GPU does, which is why it's common to have problems in the ~90C range instead of 100C+ like the GPUs themselves are good for.
Also on these cards dust tends to collect in the space between the two internal heatsinks, and isn't easily removed by simply spraying dust through the fan blades or through the rear exhaust.
My 2x 4870x2 benched better than 560ti SLI so I'm not surprised at all about that also holding true when comparing just one of each card.