"Unknown CPU Type" is just a BIOS thing and shouldn't make any difference how the cpu runs.
Check and make sure the BIOS version you use supports the CPU, if not - see if there is an upgrade that does.
It's possible that your motherboard didn't originaly support that speed of CPU either.
Check and make sure the BIOS version you use supports the CPU, if not - see if there is an upgrade that does.
It's possible that your motherboard didn't originaly support that speed of CPU either.