Unolocogringo :
Yes you can SLI different manufacturers cards.
Although if the GPU clocks are different, they will both run at the slower cards speed.
Sometimes, but very rarely you man need to update the cards bios.
Now would you happen to be aware of the minimum wattage for the power supply, in order for it to handle the two cards? I currently have a 650 watt Corsair, does this seem like it should be powerful enough?
Thanks U.