ABIT BP6 440BX problems

Hey Guys,

I just got my hands on a older pc and trying to get it up and running. New to the PC world so forgive any ignorance I may display.

Here are the specs before I go on

ABIT BP6 440BX Dual U/DMA66 3DIM 1AGP 5PCI 2ISA ATX
Intel Celeron 500MHz PPGA Socket 370 128K OEM x2
128MB-8ns 168pins PC100 16x64 SD-RAM
Pioneer DVD-104S 10X40 DVD-Rom Slot Load OEM
3COM 3C905CTX PCI 10/100 Network Adapter w/WoL Bulk
Sound Blaster Live! MP3 Plus
ATI All-In-Wonder 128 128-bit 32MB AGP OEM
IBM Deskstar 34GXP DPTA-372050 20.5GB U/ATA66 9ms/2MB/7200rp

Ok when I start up the computer I get this error

CMOS checksum error - Defaults loaded

When I go into the bios I see that the CPU operating speed is only at 300, when it should be 500 (right?) so I can change it to 500 and save the settings. BUT if I do that it will not turn back on again. So I have to shut off the power supply and turn it on again. In doing that the operating speed is changed to 300 again

Now I can tell it to load setup defaults and it will restart. When it comes up again I get this error message.

CPU is unworkable or has been changed. Please recheck - CPU SOFT MENU

Could it be a bad battery? Bad motherboard? The previous owner says it sat for a long while unplugged. The reason I think the battery is bad, is because no matter what I do the date always defaults to Sat Jan 1 2000 0 : 0 : 0 when I restart it.

Any suggestions? Do you need more information?

Thanks. My next question is how? Where would the battery be on the motherboard?

*Ignore my previous questions. I found needed information by searching around.