titovas821 :
Gingerbread :
In theory yes, in practice not really. Question is why would you do that?What is your planned setup?
Right now I'm on 8gb of ram single-channel and i'm thinking of buying a new gpu . But the problem is that it will run not really good on single-channel so i'm thinking of buying another ram stick of 4gb ram since I can't afford 8gb stick. Also I've seen that 12gb(1x8 and 1x4) performs quite nicely compared to 8gb dual-channel.
Buying a discrete GPU will not be affected by your system memory in any way. The GPU will have it''s own vram onboard.
However, running system memory in dual channel will improve performance. But don't buy a 4 GB stick, as I said above it's no guarantied to work. Keep what you have for now, save up...