I already have assembled the parts I needed to get the computer setup. But I am trying to get the cheapest amount of money to be spent on the graphics card. I have chosen the Radeon HD 7950, but will I need two of them to run at 3840x2160?
No single GPU graphics card can run 4K very well, not even the 780 ti or the R9-290X. You'll need several of the most powerful cards on the market to push decent fps at such a high resolution. To obtain that will cost you a pretty penny. I'd say $1,500 on graphics cards alone would be the least you could spend in order to get almost the same performance at 4K that your 7950 would get at 1080p. Sorry, but the processing power still has to catch up to the display technology.
No single GPU graphics card can run 4K very well, not even the 780 ti or the R9-290X. You'll need several of the most powerful cards on the market to push decent fps at such a high resolution. To obtain that will cost you a pretty penny. I'd say $1,500 on graphics cards alone would be the least you could spend in order to get almost the same performance at 4K that your 7950 would get at 1080p. Sorry, but the processing power still has to catch up to the display technology.