Check the empty(?) pads/thru-holes betwixt VRAM and the soldered RAM. If empty, the only way to use the ROM SIMM is to install the socket where Apple must have decided it wasn't necessary to do so after the early production unit ROMs field tested well.

Now to look at my MoBo for the spot, Apple placed a select/de-select option for the ROM SIMM on this (assumedly) early production unit. :approve:

The header at J18 is for 605/475 Gestalt ID selection, correct?

edit: beat me again, uni!

p.s. Does anyone else have a 605/475/AIO equivalent with the factory installed ROM SIMM Socket?