GTX 780 OC 6GB vs. R9 290X 4GB Overclocked at 4K
 

If you have your sights set on 4K gaming, and you need to know which graphics cards can get the job done, make sure you read our GTX 780 OC 6GB vs. R9 290X 4GB Overclocked at 4K article. We take the ASUS STRIX GTX 780 OC 6GB video card and run two in SLI and overclock both of these at 4K resolutions to find the ultimate gameplay performance with 6GB of VRAM. We will also compare these to two overclocked ASUS Radeon R9 290X DirectCU II CrossFire video cards for the ultimate VRAM performance showdown.

http://www.hardocp.com/news/2014/07/...clocked_at_4k/