Currently, this is the build I have been using.

I have about $800 to spend, and want to upgrade my video card, get a better CPU, and get more RAM.

I am going to get the RAM you see on the link, so $75 is gone right there. However, I don't know which CPU or Video Card to get. I would prefer that the card by an R9, and the CPU 8 core, if possible. Don't worry about required voltage, I can deal with that myself.