Crossfire 5770's

I plan on possibly crossfiring two 5770's together if I end up buying another one. I just want to make sure that everything will work together. The 5770 that I have is a visiontek and the 5770 the I would buy is an XFX (with these being different brands would they still work together?). Once I get home I can post my motherboard to see if that will be compatable but wont it just say on the box if its crossfire compatable? 

 

As always thanks for the help!

Thats who I am talking to. I have 3 PCI-e ports. The one on the bottem wont fit the card as its to close to the psu. The one on the top is very close to my cpu fan so before I install them I have to take off the fan and re apply it and make sure that it is pasted on a little higher so that it doesnt hang so low.