skeletor
Chosen of the Omnissiah
85 degree is completely fine for HD 7970. People here are just paranoid. When they read reviews, they forget that most reviewers are from cold countries. Instantly add 5-10 degrees for Indian conditions especially if you're in North India.^^^
its really not about days and stuff. .every class of card comes with a designated max temperature.
For example 85ºc would be fine for a r9 290 as its built to operate in those conditions but its not safe for a r9 280x.
As for op's problem r9 280x suffers from artifacts.
If you aren't getting artifacts, there is no reason for RMA. Infact the service people will return the card saying there's no problem. Any latest fabrication process is tuned much better to deal with heat than 10 years back. That's why AMD exploited it for R9 290X. Both R9 290X and HD 7970/280X are on the same fabrication process from the same company TSMC.
Secondly, the OP is not suffering from artifacts. gt0gagan is.