Did i damage my GPU?

[CatCloud]

So i have a Sapphire r9 280x Toxic i use in my spare rig for mining, got it rolling @ 810 Kh/s @ 77c~

Anyway Thing is i wanted to lower the volt abit and then suddenly i se artifacts on my desktop, so i close all programs, still there then i reboot my PC, they are gone, phew.
everything seems to work but when i start up Cgminer its mining at 40 kh/s instead......i lower the settings to my old settings that gave me 750 kh/s and im still getting 40, another thing thats bothers me is my pc is "lagging" now when and ONLY when im mining, i had no problems before.
No artifacts are showing, temps are ok,  GPU is behaving normally aside from the mining part.
No weird smell either 

Did i damage my GPU?
Did the drivers get corrupted?
Did i damage the PCI-E lane?

I haven´t tested gaming yet, downloading Hitman Absolution right now for testing.

Suggestions??

 

[Levent]

lower your cgminer settings dramatically like set intensity 10 and decrease concurrency to 8096 see if you start to score closer to your previous result

[CatCloud]

lower your cgminer settings dramatically like set intensity 10 and decrease concurrency to 8096 see if you start to score closer to your previous result

Didn´t help, shows even less instead

EDIT: Ok i somehow manage to fix it. "phew"

[Tigerbomb8]

Reinstall drivers..