Please help me iron out my rig issue

[Lozzyuk]

Hi all I've have been mining for a while now with a single Msi radeon 7850

I managed to bag a bargain and now have another one  since having both in the machine I have only been able to mine for about 20 mins before gpu 0 goes sick now I don't have my display plugged in to this card it's plugged into gpu 1 when mining gpu 1 is about 8 degrees hotter than gpu 0

Cgminer reports that it is sick and hangs I cannot close it with out rebooting windows but if I leave it hanging I can still use windows

Now when I run the machine with one card running the machine is fine and will mine away happily

Im only using low intensities 12 I'm thinking it could be down to the power supply?

Many thanks