Lookin' good overall.
A few notes:
I can confirm that board works with at least 5 cards as i am running 5 270s on it with no issues.
Once you get it assembled definitely check back in, preferably to this thread!
Hey Apt1916.... I have something a little weird going on. UPS brought my box of goodies and I started to assemble the rig. For right now I'm just running
1) 1200w PSU and 3 R9 280x cards. One GPU on MOBO, and one GPU on 1x riser. Windows 8 sees them in the device manager and all is good. The problem comes in when I install the 3rd GPU.
The system immeadiatly boots when I turn the PSU on, I don't have to hit the power switch. The mouse works fine before and as windows loads, but within 10 seconds of loading the slows down, and stops working. Weird. This happens with 2 GPU on the MOBO, or on 1x powered riser, or 16x riser. All tested in different slots.
I think the problem may be related to the PSU, which has 2 12v rails, not a single rail. but there only 3 PCI-e 8 pin power sockets on the back of the PSU, and no markings as to if they are on separate rails or not. Nothing in the manual either.
PSU is a Thermaltake 1200w M bronze. I'm thinking the 2 rails are the problem, but am not sure how to work around it. Cut the risers and treat the single PSU as if it was 2? Do the same when I add GPU's 4,5,6? My risers are powered 1x-16x from Amazon, and have the power wires from the molex soldered into the 16x side of the riser board... Cut those loose and solder onto the cut wires on the riser?
Maybe the mouse is just a side effect of some kind? It's a logitec USB wireless running on windows drivers, runs fine with 2 GPU's, but not 3. Not sure if there is a connection there or not.
The whole thing is beyond what experience I've had in the past, and has me a little befuddled.