Briefly, give yourself a stable point from which to depart and to which to return. Remove all of your potential upgrades and reinstall a minimal configuration of the original cards, processor and RAM. Reset the MLB. Get the whole to boot and show the HDD. Prepare the HDD, install a workable OS, and include extensions and CPs that will be needed for the upgrade. Make sure that this gives you a stable working machine.

Then only begin your upgrades, in the order processor, RAM, video, other cards, one at a time, resetting the MLB after every configuration-change, and assuring yourself of the stability of each new configuration before you proceed to the next. Only thus will you be able to recognize and repair either glaring or subtle faults, and disabilities of configuration that prevent you from reaching your intended destination. Don't abandon any diagnostic procedure because it failed at a single attempt. A known-good external SCSI startup volume will be of inestimable value during the process.

This would have been your best course all along. 'You don't ever know where you're arriving at unless you know where you came from.'

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