5th card droping kh/s , whats wrong?

[barabashko]

I have 5 cards on mobo, 280x. Using 2xPsu, 1kwt and 700wt.
USing BAMT 1.2
OC' on gpu to 1100
Card GPU0 droping kh/s after 15-30min of minig.
Slowly loosing speed from 770 to 550 and lower.
Other cards are ok.
Tempr is 55c
What can i do?

[1715055579]

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[1715055579]

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[goldbars]

I have the same issue 3 cards mine at 740kh/s while one does 620kh/s and all are the same cards

[maxman190]

I think it might be the power issue. 5x 280x recommended watt is 1800... Also, you're OCing all of them, which requires MORE power.. Suggest you replace the 700 for a 1k.

[barabashko]

750wt PSU (2 cards) and 1000wt psu (3 cards)
How to understand which slot is that GPU0 ?

I have one more 1200wt psu nearby i can test it out but i dont know which card power to replace

[maxman190]

750wt PSU (2 cards) and 1000wt psu (3 cards)
How to understand which slot is that GPU0 ?

I have one more 1200wt psu nearby i can test it out but i dont know which card power to replace

GPU0 should be your first card in the first PCI slot. Try plugging 2 cards into 1000PSU and the 3 card into the 1200PSU and see if it fixes it. And, IF you can, try plugging all the powered risers and motherboard with the 750PSU or the 1000PSU.

[barabashko]

first pci-e is 1x or do you mean first pci-e 16x?

it will take me 2 month to get powered risers and i dont have one

1800wt for 5 cards? its a joke, right? 1250 for 4 x 280x toxics is working fine for me

[maxman190]

first pci-e is 1x or do you mean first pci-e 16x?

it will take me 2 month to get powered risers and i dont have one

1800wt for 5 cards? its a joke, right? 1250 for 4 x 280x toxics is working fine for me

If you don't have powered risers, how are you using 5x 280x?

[barabashko]

and why do i need powered risers? 
Like as allways im using non powered risers. That my forth rig and i have no problems since now