Well XP-Ms are unlocked so if your BIOS allows manual multiplier changes, you should be able to lower it. So CPU-Z shows the multiplier remains the same?
I don't know your board but is there any chance you also need to change a jumper?
K8N Neo2, Opteron 180, 2GB G.SKILL PC3200, 9600XT, Cooler Master CM 690/RP-600-PCAR
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AN7, XP-M 2800+ @218x11, 1GB HyperX, AIW 9600XT, Antec Super LB/TPII Blue 480http://classicplatforms.com
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