Can I OC more?

I've OC'd my AMD 7750 from stock 2.7GHz to 3.0GHz.

It not the black edition so the multiplier / clock ratio is locked to a max of 13.5.

The CPU freq. is 227 MHz. The multiplier is 13.5. The voltage is 1.4v.

My PC's stable for over 8 hours of Prime95 testing and the temps seem pretty low - 34c idle, 42c after 8 hours of stress testing.

So, if I up the CPU freq. untill it becomes unstable, can I then give it a little more voltage and keep going like that until the temp under stress testing becomes a bit too high?

I've read that 1.5v is really the max you should ever use. Is this true, or is it limited by the temp of the CPU.

Also, I'm using HWM BlackBox 2.0 to monitor the temps. How accurate is this likely to be?

Thanks in advance,

Mike