1080p works, 1440p crashes

Hi,

I recently ordered a new Monitor with 1440p, FreeSync and 144Hz. Before that I had a 1080p 24" Monitor and had no issues playing any games.

Unfortunately all my Games crashes with the new Monitor in 1440p, but not in 1080p, even on the same Monitor! As soon as I Change the Resolution to 1440p, the game crashes within 3 Minutes of playing to the Desktop.

I allready reinstalled Win 10 and got no more Errors in sfc scan.

I'm running a Sapphire R9 Fury Tri-X via DisplayPort, Crimson 16.7.2.

Help is appreciated!

RIG: i7 4790k @ Stock, Asrock Z87 Extreme4, 16GB Crucial Ballistic Sports @ Stock, 630W BeQuiet Pure Power L8

Cheers

If you Need any further informations pls tell me!