the problems is with your FSB Settings my Friend, it is happening because your Intel P-4 is actually set with 533 FSB (means 133 Quad Pumped to 533), so makes your clock multiplier @ 2530/133 = 19
now this clock multiplier if multiplied with 100 (means 400FSB) 19 X 100 = 1900 (almost 1.89 Ghz).
so now what u have to do is: change your FSB seettings to 133, rather than 100, and it will show 2.53Ghz.
these settings can be changed either with jumpers or via BIOS as well.
and if when problem solved, send me chocolates
Intel Core2Quad 2.66Ghz 12MB L2-Cache
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LG L246WH Flatron 24"