Help needed - Sempron 3000+, ECS NForce3-A (1.0A) DDR400

Ok as above I got a sempron 3000+, which I bought off ebay, its only a month old and seems to be ok, but the print has come off the chip with thermal goop, so I can't establish the exact revision/version of the 3000+.

Also have an ECS NForce3-A which I got from ebuyer. It's supposed to support 266/333/400, socket 754 64Bit K8's (I know the sempron is a 64 bit from the box).

Now, according to AMD site all the 64 bit sempron's have 400FSB, but when I put my own 333 DDR in it, it boots gets through the copying files stages of XP install fine, then blue screens on reboot. When I put the 400 DDR in it, it refuses to even boot to BIOS (no beeps either). I've flashed bios to latest version.

Any ideas?

Already sorted

I installed xp pro on a spare disk I had lying around, checked and ghosted the original hdd and ran cpuid - it identifies it as E6, the memory as 166Mhz and the CPU FSB as 201Mhz - I've returned the 400 I bought and ordered some better stuff.