Here's the situation. I bought two of these cards:
SAPPHIRE 100354OC-2L Radeon HD 7870 GHz Edition 2GB 256-Bit GDDR5 PCI Express 3.0 x16 CrossFireX Support Video Card
One came DOA and it was discontinued so I got my money back and bought one of these:
XFX Double D FX-787A-CDFC Radeon HD 7870 GHz Edition 2GB 256-Bit GDDR5 PCI Express 3.0 x16
So Now I am trying to run them both in crossfire mode and when I uninstalled and then installed the latest drivers there is no crossfire option.
Im not overclocking any of them and using Catalyst version 13.12
Using Windows 7 64 bit
Motherboard is a Gigabyte 790FXTA UD5
Processor: AMD Phenom 2 X6
Power supply: Coolermaster silent pro 1000W
Never had an issue with crossfire before. I upgraded from two hd5770s
Both cards are obviously by a different manufacturer but are both 7870 GHZ editions
Is it because they are different manufacturers?