I've read on internet that you could crossfire a r9 290/290x -> r9 390/390x with the new catalyst 15.7. I have a sapphire r9 290 tri-x oc and i would like to buy another one but a little bit different, a GIGABYTE Radeon R9 390 G1 GAMING 8GB DDR5 512-bit. Could this configuration work? My tri-x is 4gb and this gigabyte is 8gb and I've heard that it reduces the vram to 4gb like the old one present in the computer. And the PSU is Corsair TX850M.