For the vid card, you should probably take a look at this. Tom's Hardware has a great list that is updated every month, and they have the benchmarks to backup their recommendations. The latest GPU releases have stirred things up again, so the Radeon HD 7850 is hot right now at $260 USD.
Ok, this we should probably take care of. Your poor quad is suffering from bandwidth starvation! There is no reason that you should not be able to install 4 sticks of RAM into that mobo, so something is wrong.Originally Posted by girlyxgamer
For starters, see if the other stick of RAM works by itself in one slot. Just swap your RAM sticks and see what happens. Also, should probably do some memtest runs on each stick. Best way to do that is to burn the memtest ISO to a CD, boot your computer from that CD, and let it run overnight (one stick at a time, so two nights). Check it in the mornings for red errors.
My guess is that one of your sticks of RAM is bad, which should be covered by a lifetime limited warranty. Other possibilities include outdated mobo BIOS, faulty RAM slot on mobo, dirty power from wall outlet/PSU, etc. In any case, for a gaming system, we should really track down this issue. Losing a channel of RAM is bad for performance.