Mate,
Those R9's run hot.
I had a situation where no matter what I tried the user was still getting crashes. His R9 was on water, BTW.
Eventually he opened the case and left it open. Bingo! no more crashes.
Attached is photo of his case. He certainly had enough air flow, well I thought that he did.[ATTACH]8951[/ATTACH]
Just as a side note, did you have a look in c:\Windows\Live KernelReports\WATCHDOG
