mine was in an existing smoothwall hdd, (p120) moved it to a new computer (pii) and hoped it would work fine with no action.
leaving the BIOS at defaults, on boot it had the 99 99 99 during boot phase.
then re-building from scratch didn't work either.
wasn't til later with either clocking it back in bios or using the 40 pin cable that it fixed itself and the lightbulbs over the head started going off