I tried the -current option POWERNOW_K7 on my laptop, but it reset hard
before even printing any text (that I could read, anyway). An identical
kernel without the option booted ok (I tested it to single user mode).
This is how my cpu is identified by a 3.0 kernel:

cpu0 at mainbus0: (uniprocessor)
cpu0: AMD Athlon XP-M 1900+ (686-class), 1599.65 MHz, id 0x680
cpu0: features c3cbf9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR>
cpu0: features c3cbf9ff<PGE,MCA,CMOV,PAT,PSE36,MPC,MMXX,MMX>
cpu0: features c3cbf9ff<FXSR,SSE,3DNOW2,3DNOW>
cpu0: "mobile AMD Athlon(tm) XP-M 1900+"
cpu0: I-cache 64 KB 64B/line 2-way, D-cache 64 KB 64B/line 2-way
cpu0: L2 cache 256 KB 64B/line 16-way
cpu0: ITLB 16 4 KB entries fully associative, 8 4 MB entries fully associative
cpu0: DTLB 32 4 KB entries fully associative, 8 4 MB entries 4-way
cpu0: 8 page colors

It was advertised as having PowerNow! features, so I'm assuming it has
them. Anything in particular I can do to help debugging this?

-Olaf.
-- 
___ Olaf 'Rhialto' Seibert      -- You author it, and I'll reader it.
\X/ rhialto/at/xs4all.nl        -- Cetero censeo "authored" delendum esse.