so im trying to mine with 2 cards (7950/ 5770) and every time i try to load cgminer it crashes. using one card works fine but not two. how would i go about fixing this.
Don't use 5 & 7 series cards together, they don't play nice with each other.....
ok another question would a 6950 work with the 7950 and would the two be able to get enough power from my 750 watt psu?
Series 5xxx & 6xxx are OK together, 750w SHOULD be enough for 2 cards ONLY if it's a quality PSU with at least bronze+ certification. I'm currently running 4 gpu's (5970,5870 & 5850) on a 850w gold PSU - and that's maxed out. I run all my 7xxx series cards separately on their own rigs with no worries. A good link below for you to check your settings & play with:
https://en.bitcoin.it/wiki/Mining_hardware_comparison#AMD_.28ATI.29Good luck. Peace.
EDIT: Try and get in the habit of counting gpu's and not cards, as some cards (notably 5970) have two gpu's so will be displayed as two gpu's/cards by mining software.