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CrossfireX unequal GPU usage

Last response: in Graphics & Displays
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November 13, 2012 2:40:51 PM

I have a Sapphire AMD HD 7770 and an Asus AMD HD 7770 2gb twin fan which i put in a crossfire setup, everything worked fine, CCC was detecting crossfire and was enabled, GPU-Z showed crossfire was enabled but the difference in b us width and bandwidth of both the cards was huge, the Asus card which occupied the 1st PCI-e slot had a bus width of 128bits and bandwidth of 73.6Gb/s which is normal for a 7770 card but my 2nd sapphire card showed a bus width of only 32 bits and bandwidth of only 18.0Gb/s, where as the only difference between the 2 cards was that he Asus card has a memory of 2 gb where as the sapphire has a memory of 1 gb, and hence in crossfire I know the memory of Asus will come down to 1Gb but can anyone explain why the sapphire card gives so less bus width and bandwidth as both the cards should have the same specs, and yeah on very rare instances does gpu-Z shows that my sapphire card has bus width of 128bits and bandwidth of 72Gb/s, even while gaming I cant see any increase in performance please help.
P.S- My drivers are upto date infact I even formatted my whole computer just to get over this problem still no luck, my mobo is a Asus Maximus V gene and the 2 pcie slots work as 8x incase of crossfire/SLI, my PSU is a 700watt Corsair GS700 and have 8gb of RAM my processor is an intel i5-2500k and hence dont think it will get bottlenecked.
November 13, 2012 3:09:28 PM

and yeah how I can I check GPU load while in game? any software?
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