I have a Pentium 4 2.8 gallatin core CPU which runs at 1.8GHz. Overclocking it using software will reliably beef that up to 2.4GHz.
Is this right that the CPU without O/C can only run at 1.8GHz?
And if it should be running at 2.8GHz without O/C what do I need to do to fix this?
The MoBo is a Gigabyte GA-8SIMLH-P which supports 533MHz FSB and a 0.13 processor, HT Technology.
The Computer was fitted with a Celeron 2.6GHz CPU which DID run at 2.6GHz and was able to be overclocked to 3.1GHz reliably.
Any comments please as I changed the CPU over in the hope of a dramatic improvement of performance!

I believe your 2.8GHz Gallatin is an 800FSB CPU & was designed to run at 14 x 200MHz. Since your board only supports 533FSB, your CPU will run at 1.87GHz (14 x 133MHz) unless it's overclocked.

Your 2.6GHz Celeron (D330?) is probably a 533FSB CPU, which is why it ran at the correct speed.

So it would seem that your problem is that you got a CPU that's not supported by your motherboard. You have 3 choices.....

1. live with it as-is
2. replace the CPU with one that's supported by your board
3. keep the CPU & get a board that supports it