(snip)

doesn't support a FBS of 333 but the KT333 should, right?


Yes it should. But there might be good reasons Gigabyte doesn't
officially support 333 MHz on this board. See b) above.


Well, it should according to http://www.via.com.tw/en/apollo/KT333.jsp
but apparently this isn't the whole story since in the chipset's white
paper only up to 266 MHz bus is mentioned.
Apparently official 333 MHz support was added with a later revision and
VIA conveniently choose to not mention it in the link above.

Regards
Nikos