I already have one Asus HD 7770, but since i cant afford to buy another, my other hd 7770 will be an XFX. I will clock them to the same speed, no worries.
For crossfire it doesn't matter if they're clocked the same speeds.
My concern is the amount of power these cards will need.
7770 are 80W cards.
Will I have to buy a nbew power supply to cope for an extra HD 7770? If so, how much Wattage am i aiming for?
For an overclocked i7 and crossfire 7770s, a good 450W PSU should be more than enough.
Also, both cards are top ventilating. I think the XFX has better heat sinks and airflow, so i will put it on top, making it the boss card. Does this matter?