upgrade my current machine, a G4 867mhz Quicksilver, to a new G5
Starting out I had in the case, the mother board, a number of fans, the startup drive, optical drive, and four drives set up as a RAID. later I added two more in Raid configuration... We again started to run out of storage, so it became time to upgrade.
I decided to go with different RAID cards. While Highpoint's 1820A works great on the Mac, SMART status was not available, so I bought two of Highpoints RocketRAID 2220 cards. One problem and I think it's sort of a pain, is that some of your RAIDs may not survive the upgrade of the card, so have a backup of the RAIDs. Other then that the cards work great in the Mac.
I then added my additional drives, I'm at 13 now, plus the optical drive. After getting everything connected up for the first time, I turned on the power, the computer started to come on, but a second later turned off... after a little detective work, and this is something I was afraid of, I found the stock power supply was not enough...
After looking around on xlr8yourmac, I decided to try making a wire harness to convert a stock ATX power supply into a mac supply. I have done this with a "Yikes" model successfully, this was a quicksilver though and I knew I was missing the 24v+, but I thought the mac might just pass that on... long story short it didn't and would not boot...
The solution I came up with was to keep the mother board powered by the stock power supply and using the 600 watt supply to power everything else. After searching around online, I found the following link on how to convert the ATX power supply into a Lab power supply and keep it on without a computer...
http://web2.murraystate.edu/andy.batts/ps/POWERSUPPLY.HTM
You don't need to mod as much as the link shows, I just needed the info on the 10 ohm resister to again wire into a harness (I like to keep the actual supply stock so that if it fails, I can easily get a replacement) so that I could at the flip of a switch turn on the auxiliary power supply and power up everything else. After connecting everything up it worked perfectly, the one thing I didn't like was the secondary switch on the back of the computer, after a little more thought I decided I would fix that as well.
My goal was to be able to push the power button on the front of the computer and have everything start up normal... like a Mac, so I needed one power supply to turn on the other... how? With a little Relay. I found one from Radio Shack that was a 10-volt model that trips immediately, that way after the mother board does its self tests, the drives are powered up and ready to boot the server.