How long have you had it ?Is the fan working on the card ? Not a good idea to keep running it at 90c and since your other components are at near normal temps I would suspect that the card is either not being cooled correctly or it is failing. You can try removing the heat sink and reapplying thermal paste. Can you clean around the heatsink , maybe a vaccum or canned air.
i bought that card in march 2010 so 1 and half years and 1 more thing i forgot to address is when ever i switch on my pc the cards fan doesn't turn on i have to turn it with something.