Dual GPU Issues

[glitch003]

Hi, I have a few 5830's and I'm trying to run two on one motherboard in Linux.  They're both recognized, but when I activate the second card the total MH/S drops in half, and the second card therefore doesn't add any MH/S.  I can see both GPU's (Cypress 0-0 and Cypress 0-1) but when only one GPU is running, it gets 250MH/S but when I add the second GPU it goes down to about 120MH/S on each GPU instead of 250MH/S on one GPU.

Is this a known issue with linux and multiple cards?  I don't seem to have this issue on windows.  I'm running Debian Linux and like I said, it's great with 1 card, but terrible with 2.

Thanks!

[Epoch]

The symptoms you describe sound as if you have assigned 2 separate miner instances to the same GPU. Make sure the 1st miner is set to Cypress 0-0 and the 2nd miner is set to Cypress 0-1.

[deslok]

If you installed a crossfire cable, remove it.