If you're trying to upgrade from 68030 to 68040, then you may also want newer scsi chip. You need it regardless.
i just offered it here, its expensive and little room for making $, hence i don't want to order too many.
http://www.amiga.org/forums/showthread.php?t=38747To do 040, as almost all A3000 were delivered with the revision combination of DMAC-02 and RAMSEY-04. The problem with this combination is, the DMAC-02 does not like 68040 boards like the A3640 due to heat and timing problems. Though, I have heard of DMAC-02 being ok with some 68040 boards.
Keep in mind even after you get newer Ramsey 07, Super Buster 11, Super DMAC 04, WD-SCSI 08 , there's no guarantee your miggy will like 68040. However, the SCSI 8 chip is a must fix for any amiga 3000 regardless of cpu.
If someone here has the chips, than I recommend you buy their Amiga 3000 motherboard also.