3xPCIe Mobo with 2x5830s. What do I sneak into the last slot?

[st4rdust]

My gigabyte mobo has a third PCIe slot open with two 5830s occupying the first two. It's only enough room for a single slot card, which I believe the best available is a 6850.

My PSU is a PC P&C 750w single rail unit, already powering two 5830s, three hard drives, i7 CPU & 6gb triple channel DDR3 RAM. Would a third card be pushing it in terms of overworking the PSU?

[teflone]

You can put in  4 5830's according to others, I havent tried.

I have currently 2 x5830s and a 5770. on a cheapie 750wPS

and a 3 x 5830 setup on a good 750wPS

[mikeo]

Take off the case side panel, get a 1x-->16x PCIe extender from Cablesaurus.com and hang a third 5830 up near the top with twist ties. Working fine for me and all the cards will run a little cooler.

[abracadabra]

3 5830s with an i7 would be pushing a 750W to it's very limits.

right now:

each 5830 is about 180W * 2 = 360W
i7 (depending on the version) should be about 130W
maybe 35W each 2GB stick * 3 = 105W
mobo = about 50W
each hard drive about 30-40W * 3 = 100W

that's 740W

I don't think you'll be able to runa  3rd gpu on that psu.

[st4rdust]

Good point regarding the power limit. Last thing Id want is for three graphics cards crap out from power issues.

Also, I want to make sure that, even though I know they can't be crossfired, I can run a different type of card in said 3rd PCIe slot and mine with it. For example, my two 5830s and, say, a 6770. Though they can't crossfire, will I have any issues running each as a miner?

[abracadabra]

no, i do that all the time.