gtx 780 temp, fps, lines in every game

Sitnoff

Reputable
Jun 21, 2014
69
0
4,630
Hi..
brand new pc with gtx 780 [dc2 oc, overclocked out of the box] & 4790k at 4/4.4ghz
it is running with the latest drivers, first hours of this pc life
I am depressed of my performance
1. after 5mins of playing metro last light fps is falling to 10-15
2. I have translucent lines on my screen in everygame even with vsync on or off..
3. in metro or far cry 3 gpu temp at 93* and cpu 55-60*
Sometimes in metro LL i have a decent fps, but sometimes it falls to 5-10..far cry has a bit better fps but that game is full of those lines on my screen
im angry and depressed of that strange thing, dont know what to do
any help is appreciated...