You could try this:
1. Download SetFSB
2. Set clock generator to RTM876-665
3. Click "GetFSB"
4. Move to 65, click setfsb
5. Move to 75
6. Click setfsb
Done
2.964 GHz (3.0GHz basically)
I only know how to do it without bios, but there is a youtube video out there explaining how to do it with bios. Just google overclock pentium e5200 2.5 and it's usually the first or second video to pop up.I DO NOT RECOMMEND GOING OVER 75 (2.9Ghz)!!! My system blue-screened like 7 times already trying it out. Just a warning.
The move to 65 helps against crashing during the overclocking of the CPU. I assume signal skipping of some sort might be a cause, crashed on my a couple times jumping straight to 75.