What are the highest voltages acheivable on K7N2 Delta-L?

I just built a new rig and i want to OC it major. The manual that came with the mobo said it was optimized for overclocking but it does not support Vcore over 1.80 in the bios, is this a bios issue, a psu issue, or do they never go over 1.80v in the vcore?

Thats it and there is no volt mod for it either. This board is a mild O/Cing board