Cpu overclock

HY I TRIED TO OVERCLOCK MY I5 2500K, BUT I DID NOT DO IT IN THE END
AFTER A WEEK OR TWO, I OPENED REAL TEMP, TO SEE MY IDLE TEMPS. I WAS SURPRISED TO SE THAT THE FREQUENCY WAS BOUNCING UP AND DOWN, 3.4-3.7-2.9
THENEXT THING I DID IS TO CLEAR MY CMOS. WELL REAL TEMP STILL DOES THAT.
NOW I HAVE A CLOCK PROBLEM TO. WHEN I SHUT DOWN MY PC, THE CLOCK STOPS.

Thing is that cpu-z shows 1.6 in idle, all suite 2 from asus shows 1.6 idle
but when i look at the idle temps they are high, and they bounce.

My motherboard is asus asus p8z68-v pro

You didn't watched small movies or read something about overclocking your cpu ?
You must to stop from bios power saving , and then raise the multiplier to 4.1-4.2 i think will be good without raising the voltage.
That bouncing frequency is because when your cpu is not used is droping down the frequency and when you do something what need your cpu then is raising.