I just did rev D firmware and it was FAST! when it worked. Had to reboot about 20 times to get one good boot :)
C firmware did the same thing but I didn't test it much. BOTH gave the checkerboard pattern on the screen most boots.
I am just now running B and it boots properly to 7.1 on a...
I can't add too much at all to this but soaking it all in for potential usage when I tackle my own 5126 machine. Mines recapped but still has a bad power handler since it will not power up a SCSI drive except for the low power scsi2sd. I got it used and that is okay. At least I got one in...