I already have it running at 1.79ghz.
What does you BIOS report when running that speed?
At default values.....it comes back as a 1900+?
Have you tried unlocking the CPU?....are you running a non-default multiplier?
The reason I ask is sometimes people don't fully unlock the CPU and they think they're running a particular multiplier...In reality, the motherboard defaults to another multiplier and a different speed is reached...
Its a long shot.....but who knows....