mobo or cpu?

I have an epox 4sda+ with p4 1.6a. The system will not post at the default settings. I get an error code 3C "Expand compressed BIOS code to DRAM". I then have to set the cpu vcore jumper at +.10 volts, and the system starts, showing the cpu vcore as only 1.16 volts. It's really amazing that this cpu will start up with such low voltage. I can then change the bios settings, and use the cpu vcore voltage jumper to select whatever setting up to 1.85. It's running at 1.65 volts, 2.7 ddram vcore, 132 fsb, and 4/5 ratio with no problems. I would like to replace the cpu or motherboard while they're in warranty. Any ideas where the problem is?