Once I had this problem (reinstall drivers), too after flashing with other voltage parameters. After flashing to old bios everything was stable again. So probably you have a bios issue somehow.
Another thing I have figured out, when miner switch off or go to zero after a period of time which is always more or less the same amount of time - go and check temperatures. I have to keep all my cards less then 69°C. If cards go above it will cause failures.
Kind regards sworker
Well now you got me thinking. I purchased this fury off eBay. Maybe I should try finding a bios off the tech site and reflash it. Temps are actually beautiful. Fan runs at 35% @64c. And that was yesterday at 82f. This card is huge:). Or at least the heat sink is. It's about 2.5 inch longer than 7970. It's a sapphire fury 4gb oc. I messaged the guy off eBay. He says it was only used for gaming. But who knows. I will try a reflash and see where that puts me. Thanks for the info.
Edit. I'm at 11 hours mining @460 h/s. But only card in system. It's def an issue I've never come across
BR