Zapping PRAM may prevent them from starting up a. Kevin Callahan writes: "Some Power Computing PowerCenter Pro machines ship with the Adaptec Ultra SCSI card in the PCI slot closest to the motherboard. These may have a problem whereby resetting the PRAM will resulting in a persistent blinking question mark at startup. The solutions are: 1) Reboot from CD and then reboot without CD or 2) Move the Adaptec card to the outside slot.
b. Chris Heatherly (of Power Computing) confirmed this problem, noting that more information is posted on the Gigawatt page. Briefly, it states: "An issue has been discovered with the Mini-Tower configurations of PowerCenter Pro when the PRAM is reset. If you reset (Zap) the PRAM on either a cold or warm boot, the machine MAY display a disk with a blinking question mark. Boot from the Power CD, and the HD will be accessible upon the next startup and the machine will again be completely operational. Repeat this procedure if you ever need to reset PRAM."
As to the solution of moving the card: "Moving the card to another slot will allow you to reset PRAM and restart without using the Power CD as a work-around. However, the card is placed in the bottom slot on Mini-Tower computers to facilitate routing of the SCSI cable. Moving the card to another slot prevents the installation of other PCI cards because the cable will block access to the slot."
Chris adds that "We will post updates there as they are available. We have discovered the root of the issue and are currently investigating a permanent fix."