For the GPUs, I would grab the hd6870 if you can. The RAM, 8gb is what you want now, 4gb should be minimum. that won't be a good overclocking motherboard. Also, I wouldn't trust that PSU with any overclocking let alone a system with an aftermarket GPU like that. If I were you, I would look into a new motherboard and PSU. The rest looks great. If you couldn't change the motherboard, I would at least look into a new PSU.