Re: Crossfire motherboard with 1 nvidia card already isntalled, second for memory support only?
you can only use 2 gpu's with newer gpu's like the gtx460 and gtx465 i believe, but it takes some bios flashing. If you had an ATI card you can crossfire different cards as long as their in the same series, eg a 4850 and 4870, but not a 4850 and 5850.
Also depending on the board if it supports crossfire it probably doesn't support SLI (nvidia's multiple GPU interface) because nvidia usually requires a specific chipset to run SLI.
the quick answer tho is no. it won't work. you're better off using the 5600gt for a frisbee or paper weight.
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