the larger the resolution the less infulence the cpu will have on your gaming.
Think of it this way... your system is only as fast as the slowest part. At 1080p 60hz, your gpu is pushing out 124,416,000 pixels per second, which is cool because this gpu can do 200,000,000 pixels in this game (number picked at random for illustration purposes), so there is zero bottleneck on that side of things... lets say your cpu is doing X amount of processing for the game, and Y amount of draw calls for the graphics... for "xy" performance... in this case, lets say xy performance was JUST slow enough to keep your gpu from hitting 60fps... lets say it meant your system was cpu bottlenecked, and as a result your system was capped at 55fps because xy wasn't enough for this game.
now you go to a 2k (which is really 1440p) monitor with the exact same system as in the first example... the 1440p monitor also has a refresh rate of 60hz, which means to max out the game you'll need to push through, 221,184,000 pixels... which is about 77% MORE pixels then 1080p... worse, your gpu can only kick out 200,000,000 pixels in this game. which means your GPU is now a bottleneck... in this case you're actually capped at... 54fps by your gpu. the cpu meanwhile will still be required by the game to produce x processes and y draw calls (that's right, these numbers don't really change at the higher resolution) which means your cpu, though it can only do 55fps in this game, no longer is the bottleneck. Instead of getting 55fps in 1080p, you're now getting 54fps in 1440p... and it's not because of added pressure on the cpu, it's because of added pressure on the gpu.
Take this even further... lets say you move up to 4k, or 3840x2160, lets say this is also a 60hz monitor, which means to max this game your gpu will need to push out 497,664,000 pixels... but being capped at 200,000,000 you're now limited to just 24fps by your gpu... the cpu is still being asked to perform x functions for the game and y draw calls for the graphics, which means it could in theory rock this thing out still at 55fps... but your poor poor gpu is hopelessly crushed by this title... and now your system is stuck at 24fps in 4k resolution.
You see what i mean by "the larger the resolution the less important your cpu becomes"?
so yeah... i wouldn't worry so much about the cpu... if you plan to play at large resolutions you'll need a great gpu, the cpu is almost ancillary at this point. Think about it... lets say this magical cpu which was a bottleneck at 1080p is a i5-2500k. lets say you COULD get yourself a i5-4670k, and it now meant you could game in 60fps in 1080p... or you could go brain dead and get yourself an i3-3220, and further limit yourself in 1080p to say... 50fps. however... you'll never notice that i3 being a bigger bottleneck then your origional chip in 4k will you? 50fps is still more then enough cpu power... considering your gpu can't break 24fps in that resolution.
This is why if you want to actually benchmark cpus in video games you bench them in the lowest resolution you can. because the lower the resolution, the more cpu bottlenecked the fps become. the higher the resolution the more gpu bottlenecked it all becomes.
****note: all "cpu" numbers are illustrations, as was the imaginary cap on the amount of pixels this example gpu could push in a second. I used those numbers just to illustrate the general point... since this seems to be one of those abstract concepts many people don't really understand.