upgrading old processor, need help

[GhOsT1321]

I am upgrading the processor in a HP Pavillion 533w
Info on the computer Here
Motherboard Here

I applied thermal paste, the chip is in correctly, and there were no bent pins or broken pins.
The old processor is a 2.0 Ghz, the new one is a 2.5Ghz
When I turn the computer on (with the new processor in) it says "Entering Power Save Mode" and then turns off
Did I do something wrong or overlook something?

I think i found the problem
the CPU I put in had a BUS Speed of 533 MHz
my Proc. Front Side Bus Freq. is 400 MHz
Would this be the problem?

 

[Slaymate]

Can you supply a link to the CPU your trying to use.

 

[GhOsT1321]

Can you supply a link to the CPU your trying to use.

Here IS a Link

 

[Trotter]

That's a Northwood CPU. Even though the FSB is 533 vs the mobo's 400, it ought to work.

 

[Slaymate]

You should look for an updated bios. You'll probably have to re-install your old cpu, flash the bios, re-install the new cpu.