I had this happen to me last year when I bought my bookPC
Other things to check:
1. Can the board handle the chip? I tried to put a 667 in a board that could only handle 500, and had the same problems you are describing
2. Check the BIOS reset jumper. This was eventually what fixed my problem. the reset jumper was in the wrong position.
3. Check the chip on another system. It could be that your chip is dead.
4. check the motherboard. swap out chips and see if it works.
5. check the MA/SL settings on your drives. I realize you only swapped the motherboard/chip, but check anyway