the earlier verison of the asus a7v266 and a7a266 only supports the athlon 4 with 1.1 version of the pcb and nothing earlier... www.asus.com ... so there are boards that do not support the athlon 4 fully.
Re: your not very astute 'duh' remark, there are BIOS's that recognize the Athlon 4 but do not yet support SSE! This has been verified by DDR mobo - Athlon MP owners whose BIOS reported the CPU to be an Athlon 4, but (in fact) did not support SSE!
The bottom-line is that some BIOS's just recognize the Palomino, while others both recognize it and enable all of its features. Unless the BIOS actually indicates 'SSE enabled', the only other way you can tell for sure is to run version 3.0b of WCPUID (of course, you will need a Palomino in your socket-A :wink: )!