Hopefully someone might have an easy fix for this!

Been mining GPU Coin since its release, R9 290 x 4 with no problems on Windows 7. Hashing at 450 per card. Went to install a 5th card so decided to use Windows 8 to avoid problems recognizing more than 4 cards. Miner starts fine but within an hour cards start showing up DEAD or SICK! Same settings as in Windows 7 which had no problems for days!

Any ideas?