Star Brood wrote:
I get around 15-30FPS if I drop detail levels to "ultra" instead of "extreme" in StarCraft 2
Huh? I suppose 3rd person games like SC2 don't require as high of framerates as first person games, but 15fps is pretty low. I would definetly drop to "high" settings if framerates are dipping that low.
Your question is a bit complex. There are games that are GPU bound
like BF3 and Crysis 3 where it doesn't matter much what CPU you have.
Then there are CPU bound games
like SC2, Civ5, and Skyrim that will show significant performance differences depending on the CPU. Even in those games though, you can still see big improvements with better graphics cards.
(granted, the cards in that article were tested on an i7-3820 to reduce/eliminate CPU limitations)
Sure, your "weak CPUs" will hold back performance compared to the same GPU in a modern i7 system, but you'll still see noticeable improvements going from your current GTS 250 to something like a 7790 or higher. In general, the peak of the price/performance curve is in the $200 range. Anything below that, your ok, anything above that and you're paying more for the improvements you're getting. Also, what resolution is your monitor? Assuming 1920 x 1080, ~$200 GPUs will get you High-Ultra/Extreme settings and 40+ fps in most games. (for reference)
With your current CPU situation, I think you're probably looking in the right price range ($140-180). If you'll be holding on to your current system for 2 more years, a GPU upgrade around the same time as the new system wouldnt be unrealistic. Therefore Airman's
advice of spending the least amount on a GPU to tide you over is smart (7790/GTX650Ti Boost territory).
Main: i5-3570K, ASRock Z77 Pro4-M, MSI RX480 8G, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, EVGA 550-G2, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Crosley D-25 Case Mod