that model is locked to begin with xD it needs the designated K at the end of the model to indicate an unlocked multiplier. Also, 460 is OLD. Diablo 3 is probably too much for it - try to get a 650/650ti.
The 650 is ugly, and slow, and cant SLI
I'm getting a second 460, and I'll be fine..
And you can play with the multiplier on the non K's, you can't get any lower than 26x or any higher than 34x on a non K 2300.
Also, thats not the point, the problem is it wont boot with an unlocked CPU ratio (Where it slows down the processor during idle to conserve power)