Issues with connecting more than one Video card ASRock z77 extreme4

[Isaac53]

Hi all,
i build a mining rig with ASRock z77 extreme4 , I5 (4 cores) , 8GB RAM 1600Mhz, SSD 60GB
2x Gigabyte R9 280x
at first everything was fine but from time to time the system crashed and the only way i could get it back is remove one of the video card.

when only one video card is connected everything is working fine - driver is working perfectly.
btw - i switched between the cards just to make sure the video cars is not the issue(works).

now when i'm connecting the second video card the windows is starting up(windows 8) and the screen went dark. and that is it.

i removed one card went back to windows completely remove all drivers
and than restart with two of the video cards connected.
this time windows recognized both (in Device manager) - generic video driver....
however - one of the cards is showing exclamation mark saying the driver is not matched the hardware.
the other card is fine (device working properly)
i tried re install the driver and back to square one - black screen after window starts loading.

any suggestions?

Thanks a lot!
Isaac

 

[unknownofprob]

what's your PSU?

 

[Isaac53]

sorry i forgot, Thermaltake Toughpower Grand 1050W.

i did a format and install new windows(8.1 64bit)
right after installation windows is loading and under device manager
i can see two video adapter - (General Driver) but again one of them have exclamation mark and
error code 31.
i switch the cables to use different PCIE(1x,16x) but nothing helps when two video cards exist there is an issue... much before installing the drivers...

any ideas?

 

[unknownofprob]

When you connect up the two cards, how did you connect them? are you running them separately or in crossfire?

 

[Isaac53]

no cross fire, they are connected each to x16 slot - i also tried to use a cable - 1x->16x and use the other 2 pcie i have - same issue.
the BIOS detect the cards but the OS has an issue with it.
i tries another OS - BAMT - when 1 card is connected all good, 2 cards - os hangs on loading and nothing happens.
the last thing i tried is to change in the bios the Gen of the pcie - to GEN 2(not auto) but nothing help.

i really have no idea what is the problem i can only say that the cards separately works great so i don't think the card is the issue.
maybe the motherboard?

Thanks again.

 

[unknownofprob]

yes it might well be the motherboard, have you tried a different slot to make sure it isn't an issue with the slot?

 

[Isaac53]

yes i did ... and nothing same problem , it's like the motherboard only supports one card at a time.
i"ll contact asrock for RMA hopefully they will solve the issue.

Thanks again.

 

[unknownofprob]

sounds like a slot issue, if both cards works in one slot then the cards are fine, it's the motherboard here. If you need help choosing a motherboard you would like that is compatible, just message me and I'll look into one that best suites your needs.