I just built my system a week ago;
ASUS P8Z68 V PRO
17 2600k (intel Stock fan)
8gig (2x4gig) GSkill Ripjaws 2133
gtx 560 1 gig video card (ASUS/Nvida) ......
Any way the system has been working fine since i built it until yesterday. When I powered the comp on the CPU the cpu fan didnt turn on, i powered of and on a couple of times and nothing. i opened the case unpluged and repluged the fan header and also moved the fan blades a little with my hand. I powered on the comp and the fan worked. I shut down and restarted and the fan didn't start up again so i powered down moved the blades again a little powered on and it worked again. this happened once more did the same thing and worked. when the fan is running it works fine, idle temp around 35c load around 60c.
I powered it on this morning and it was fine, i powered it on probly 3 or 4 times today and it was fine, then i powered it on once more and no fan again. I took off the side pannel while the comp was still on and as soon as I slid the pannel accross the fan started. i few more boots after that and it started fine.
Any Ideas on what is going, I'm pretty sure its just the fan its self that its dodgey (and really thats what im hopeing)
Man you got that much $$$$$ in this thing get a cousair H-70 , Now more worries.
Try to increase the CPU fan duty cycle in BIOS to at least 30%.