New Mobo won't recognize full bus speed of CPU

I just got a PCCHIPS socket 462 mobo to replace an OEM mobo from an old eMachines computer that the BIOS went out on. My problem is that the mobo only recognizes my AMD 2600 XP CPU as a 1900 chip. It will boot up to Windows being underclocked, but when I try to Load fail safe defaults in the BIOS, it will recognize the CPU as a 2600 but then it won't boot to Windows. When I clear the CMOS it comes back with two errors, 1. CMOS battery low and 2. Wrong CMOS memory size. As long as I leave it at 1900 it works but it won't keep the time either. Is this an issue with my memory maybe? I have dual 512k sticks pc2700 that i took out of the old case, the new board supports DDR 400 dual channel though. Or is something else going on with it? Any input or ideas would be greatly appreciated, just want to get it to recognize the CPU as the 2600 it is and still boot up and be stable. thxs! ^^