DS3 OverVoltage failed after BIOS modified

[nvidia5700]

I changed the full screen logo of DS3 F10 BIOS. But after that, the overvoltage control doesn't work. The most important thing is I must change the voltage of memory to 2.1 to make it run at optimized latency setting. Whatever value I set in BIOS, it always be 1.8v.

Does any one have a solution for this issue?