My guess is power.... the ram chips are probably good
or he would get a Red screen on bootup. So I would say the
ram chips test good on boot but when using the ram it
draws more power and will flake out.
The SCSI/RAM card I have has 2 extra power input plugs
and it NEEDS the extras power. Without the extra power
it will boot but when I try to do anything the machine
will crash.