I too have to apologize for my English in advance.
In my rig I use a Sapphire Radeon HD7990 and I have the exact same issue!
In short - This problem started aprox 4 months ago. I too have tried the problemsolving mentioned above, all but tempering with memory clockspeeds or voltages. BF4 with mantle is not working at all. I managed to switch over to DX11 in game and it works much better, tho it crashes sometimes too. All other games runs smootly.
Driver versions I've tried: - 13.9, 14.4, 14.6 and 14.7 Beta. No improvement.
I just bought all componets beside the graphicscard new and the problem have followed me from my last pc - running Windows 7, to my new rig running Windows 8.1.
I hope to see improvements soon AMD!
Processor - i7 4790k
HDD - Samsung Evo 840 250 GB
Motherboard: ASRock Extreme 4 Z97
Grapichs Card: Sapphire Radeon Hd7990
PSU: Corsair RM 750W
Ram: Corsair Vengance 16 GB (2x8GB) DDR3 Dual Channel 1833mHz