Overclocking on ASRock, i5-2500k

First of all, a question:

Last time I overclocked, I had trouble booting up and only got it to start up by resetting CMOS and booting ~10 times. Computer was fine the whole day before that. Keyboard was also screwed. What happened?


Ok so here goes:

After fiddling with my CPU after the boot problems, this is what I've got:

4.4GHz stable on 10-pass High IntelBurnTest
Average 1.264V, max 1.29V
Max 65 degrees Celsius on all cores combined.

Settings:
CPU Ratio [44]
Internal PLL Overvoltage [disabled]
SpeedStep [Enabled]
Turbo Boost Power Limit - Short duration [220W], Long duration [200W], Long duration maintained [56s]
Core Current Limit [200]
Additional Turbo Voltage [Auto]
BCLK [100.0 MHz]
Spread Spectrum [Disabled]

Power Saving Mode [Disabled]
CPU Core Voltage [Offset] [+0.040V]
CPU LLC [Level 4]
CPU PLL [1.075V]
the rest - auto


Any comments on maximising stability? Tips on how to not face the boot problems?

Thanks in advance!