I noticed I have not been really clear as to what I have done and at what stage I am of the troubleshooting, sorry about that!
Here is a recap:
Forcing voltage to max and with K-boost on in EVGA precision, card works IF IT IS OVER 26C!! (Important! - this is my issue ). It works both stock clocks and slight OC's, as it should be.
Even though I really press my system my idle for GPU will be 23-26 (even forcing the speeds) due to my somewhat.. overkill watercooling :)
As soon as I leave my PC or surf the web for a while the card clocks down/up according to temperature in the ranges of 23-26 ( 26+ makes it go stable at stock speeds )
I got hardware monitoring logs made with EVGA precision if anyone is interested. Sometimes the card state get's "locked" in 324mhz mode, and I have to uninstall drivers/drivercleaner/uninstall evga precision/reinstall drivers for it to work with K-boost and stuff again.
A bit of the log, edited; (OC'ed a bit)
26C ; 1201.935
25C ; 888.387 ; 731.612 ; 614. 032 and finally stabilizing at 600.967
24C ; 574.838 then 535.645 ; 483.387 ; 431.129 ; 378.870 ; 339.677 and finally stabilizing at 324
<message edited by mvd06001 on Wednesday, November 07, 2012 12:25 AM>