ohiou_grad_2006 :
So at higher resolution, the GPU is working harder, so it can't feed data as fast back too your i5. Apparently when you drop back to 1080p, your GPU isn't as under as much load as at higher resolution, so it's feeding data back back to your CPU faster than the cpu can handle, hence the stuttering.
Do you have vsync turned on? If not, turn that on to see if it helps. It should try to limit your GPU to only putting out 60 fps, which your CPU should handle. You can also try turning everything on 1080p up to max with all the AA and textures etc turned up as well. That should also put a heavier load on the GPU and balance things out.
Uh, your explanation makes NO SENSE; a GPU doesn't "feed data back to your CPU" too fast causing stutter, and VSYNC has already been discussed.
I'll admit the PROBLEM itself makes no sense right now since there's no logical reason I'm aware of that you'd get more STUTTER with a higher FPS (and uncapped frame rate).
WHEN THERE IS LESS CODE (i.e. LOWER RESOLUTION) TO PROCESS EACH FRAME IS PROCESSED QUICKER. THAT IS IT. STUTTER SHOULD NEVER BE WORSE UNLESS SOME STRANGE SITUATION (MONITOR ISSUE?) IS HAPPENING.
Just FYI, but the way games should work is THIS (oversimplified):
1) Game data loads from HDD/SSD into system memory
2) CPU reads that data and performs two main types of calculations:
a) game data locally (including CPU physics) and
b) sends draw calls etc to GPU
3) the GPU processes what its told to do then creates a frame
4) frame is sent to the monitor
*If the CPU is too slow the GPU sits idle. If the GPU is too slow it sits idle but doesn't bottleneck anything else (except the monitor as in lower FPS).
STUTTERING happens for many reasons, but usually because:
a) VSYNC ON and you can't hit the FPS target (60FPS on 60Hz monitor), or
b) CPU overwhelmed (inefficient code and/or other program hogging CPU), or
c) GPU overwhelmed (inefficient code, or settings too high)
d) odd MONITOR issues (hence why I recommend to SCALE BY GPU + Scale by aspect)
I'm sure I've missed some, and frankly only the last point applies to this situation.
*Two points as I ponder this:
1) make sure to SCALE BY GPU (not monitor) + Aspect (will always send out 2560x1080 from GPU).. then on MONITOR just set to 1:1 scaling, and
2) Don't STRETCH games. Why? I'm guessing it's a performance issue, in which case just use the next lowest resolution which I'd guess is 2100x900.