Hello, I am on my 2nd 6990, the first I thought was defective, so I rma it back to newegg, now I have same issue,...1st 750w tx corsair psu, this meets the requirements for the card, exceeds them a bit actually, as far as amps goes, .....2.3 gig quad intel chip, 750i nvidia xfx mobo, 6 gigs of 667 ddr 2 ram, and the 6990....now in msi afterburner it shows 0 2nd gpu usage, lower temp for 2nd gpu, and either 250 in desktop for clock freq, or 0 in games, it actually goes to 0 inside games....also 0 usage, it is also not detecting all of the memory for the unit, same as previous one, only detecting 2760 mb, it shows linked in ccc, and it shows memory on gpu z, however in dxdiag shows 2760 mb, also, in msi, doesnt show second unit memory at all.... gpu z shows matching stats for both, except ati crossfire for second gpu, say disabled....and once again, performance, is half what it should be, and of course my mobo is a non crossfire mobo, so does that mean, that since even though these are on same card, that because my mobo doesnt support crossfire, that it doesnt support the full usage of the second gpu, I was planning to upgrade rest of system, I just would like this confirmed, or supported if anyone knows, thanks...