Whats up with my cpu?

[silver_fox]

Hi.
I recently bought a used P4 2.8 GHz cpu, to replace my P4 2.0 GHz.

Now, I've just put it my socket and started the computer normaly.

When looking at the 'system properties' window(windows-key+pause),
it says:

Pentium(R) 4 CPU 2.80 GHz
2,09 GHz

Is my cpu only running @ 2,09 GHz? (presumably yes)
If so, why? Am I underclocking it?
How would I go about changing it?

Thank you for your time, and I would be very thankful for any help.

[sapi]

Does your motherboard have full support for the FSB speed of your new CPU?

[silver_fox]

Does your motherboard have full support for the FSB speed of your new CPU?

I don't know. Unfortunatley I've got a compaq mb, and I'm having a really hard time getting a hold on the specs for it.

That would most likley be it tho huh?
Or is there any likleyhood I'm just inadvetedley running it underckocked (or undervolted)?