There are jumpers or dip switches on the motherboard that need to be reset manually for a board that old...only some newer boards will set this for you automatically.
Find the user manual for this board so you know how to set it if the board itself isn't marked with the info. You should be able to download the manual if you have the board model and rev numbers usually located in one of the corners along the edge of the board.
If you can't locate the numbers, see if there is an FCC number on the board. If that doesn't work, can you at least boot to the first bootscreen and see the ID numbers along the bottom of the screen...if you can boot that far, use the Pause button so you can write down all of the ID info and post here so we can help you locate the right board info.
TONI
I have this old P2 that I have pulled out to get running for the kids. Its An IBM aptivia 2139E5U. I didn't have the original processer that came with it so I got one from a friend. It wasn't the same MHZ and when I booted the system it says bios code is mismatched and equipment config error. I have tried reseting the CMOS and loading the defaults in the bios and still the same thing. I'm also having a hard time finding the bios driver or upgrade.

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