I have just slapped a second r9 290 into my system, after installing a 1200w thermaltake PSU. In Catalyst control centre, I can see my second GPU as "disabled," but can't find any option to enable it, or switch on Crossfire.
Old i5 760 with a Asus p7p55d Deluxe (the one with the PCI-E slots.)
Catalyst 14.1 beta drivers.
I can use the second GPU to mine (not it's primary purpose,) but I have my screen plugged into the first one.
Is there something I'm missing? Is PCI-E 3.0 a requirement for bridgeless crossfire?