You should have a cmos jumper somewhere near the motherboard battery. With the system turned off, move the jumper over one position keeping 2 out of 3 pins covered and unplug the power supply. Leave it for one minute, and return the jumper to it's original position. If this doesn't reset the bios, remove the board battery for one minute, and reinstall. If these steps don't work, you may want to try a different power supply.