So here is what I did! I disasambled my fans on Haf922 for cleaning and get the back. Clean thorougly cpu fan. The heat sink was filled with dust so I use a toothbrush to scratch it. When I did this some dust fall over my video card. I cleaned it with dust collector without removing video card from the mobo. When I finished all cleaning procedures my pc wont boot. Fans,hdd spins but monitor is still blinking and appeared nothing on the screen. After a few resets it starts normally. After cleaning video card sometimes pc fire up sometimes not. When I connect the monotor to iGPU of i52500k there is no problem - system boots without problem every time. Very strange and annoying problem. I am sure the problem started after cleaning. What do you think, what should i do to prevent this from happening again.