My question is, can I add another HIS IceQ X 6950 video card with my current psu? Many people have said it will work. Others say I need 850-1000 watts, although I know these cards aren't drawing enough to need 1000 watts.
Also I will be unlocking shaders on the second card as I found my current one supported it.
You can always get a power meter from a local hardware store and check your current system power if you want an idea of what you are using now. That said, AC power numbers are always higher then the actual DC the power supply is pushing.
Numbers for a 6970. Just in case you unlock and overclock enough.