It works on the 8890 - PCI buss stays at 33MHz, but can be adjusted separately if desired.
I have done some minor testing taking my 2.6 to 3.0 (230MHz buss). It seems to work, but, having just recovered from a virus which necessitated a full reinstall, I am a little gun shy.
Oh, I tried setting it to 3.2 (250MHz) and it locked instantly. Instant locks don't really scare me. I am afraid of accidently clobbering my disk drive when running OCd.