If your motherboard is up to date with its BIOS revision, and the CPU identifies as an XP 2500+ with BIOS default settings, then you can be certain that the processor is in fact an XP 2500+.
It sounds like you've obtained one of the 'illegally altered' processors which were included in some systems that were sold overclocked, and were the reason for AMDs decision to 'lock' the clock multiplier on more recent Barton CPUs.
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Grandad
Offline 3,826 posts
since Mar 2004