Quote from: Starscream on February 19, 2014, 09:44:36 AM

Quote from: 1369 on February 19, 2014, 04:16:56 AM

i have mixed gpus in one of my rigs, a 290x, 270 & 2 8750's, only a couple cards would work with 4gb system ram, after adding another 8 they all started, i could be wrong, but it couldn't hurt to add another 4gb if you have an extra slot & a stick of ram... or even spending $40 on a stick, better than your $$$ sitting dead.

Not needed. I'm running a 3x R9 290 setup with only 4GB.

@OP - You never mentioned it (and no1 asked either), but which version of Windows 7 are you using? If you're using 32bits than it all makes sense (it's cant detect more than 4 cores) and you'll need to install Windows 7 64bit for your 3rd card to be detected.

But in case you have 64bit, let's go back to the basics: When you plugged the cards one by one they all worked solo, yes?
You tested every PCI-e slot (those you will want to use) with a single card in the system?
You shorted the pins correctly? (A1-B12)
Did you set up the 2nd PSU correctly? (make sure you don't mix the 2 PSUs).

Right now I can't think of anything else really, other than to get a x16 to x16 riser and try that out.

When I set my rig it was pretty straight forward. I connected 1 card (to the x16), installed drivers+sdk, tested, saw it worked, went on connecting the 2nd card (to the x1 with powered riser), saw it worked, moved to the 3rd card (also to x1 with powered riser) saw it worked and that's about it.

I tested each card individually, checks good.
I tested each riser individually, checks good.
I tested each pci-e slot individually, checks good.
I have not shorted the presence pins, I've seen a lot of horror stories about it working but frying the mobo within a week. I'd like to avoid shorting pins by any means.
For the second PSU, I shorted the power wire to one of the ground wires on the 2nd PSU. I plugged the video card in to the PSU. I kept all my powered risers on the same PSU (perhaps this is my problem?? should I isolate the 1 card, riser included?).
I don't see how a x16 to x16 riser would behave any different from plugging directly into the board.

For the record, what kind of mobo do you have? At this point I'd be willing to just buy a new mobo to avoid this headache. This board is honestly shit from my current experience.