Second card very slow

[sapstar]

I have just started my first rig build. I am using 7950's. I still didn't get the risers, so using the onboard PCI-E x16 slots. When I insert two cards, one performs at around 80 KH/s and the other one at 630 KH/s. If I remove one of the card the remaining one works at 630 KH/s.

Did someone experience this before and how to fix it?

[redtwitz]

I suppose the card that performs badly is the one that doesn't have the monitor attached to it.

A video card without a monitor is considered "not used" by the OS, so it gets clocked down to save power. A dummy plug will take care of this.

[sapstar]

You are spot on. Dummy plug fixed the problem. But with 1 card, I was getting 630 KH/s, with 2 running I am only getting around 550 on each.. .