Bad performance in Borderless Fullscreen Mode

[Ranebow]

Mmm I haven't tried that.. set affinity to wich cores?

Ideally the more the better, so all eight (0-7). You could try taking them off of 0 and 1 forcing them to run only on 2-7. I wouldn't advise though, a 2600k hasn't issues with ARR.

If you are using Crossfire, Borderless uses only ONE GPU... You can see the 2nd GPU fan spin down when you use Borderless, and it comes back on during full screen. FPS gets affected similarly.

He has a single GTX 770.