Old Mac Pro G5 no video

Mister Microphone (Author)

With an initial assumption, my guess would have considered some

symptoms to potentially be a Kernel Panic. Yet all my older Apple

bookmarks, to Developer section, come up with Nothing. (wiped)

"Technical Note TN2063 - Apple Developer

Understanding and Debugging Kernel Panics"

[Those aren't Available, as they pertained to older hardware+OS.]

Web.archive.org: has scraped or dragged some of those pages.

And this archived page, suggest 34 items were saved, by dates.

While internal sub-links to bits inside; may not have content now.

This one shows from the date 06/24/2023. Maybe some are fuller.

An archive may show what might be active links; but no content.

Edited to Add: one apple developer archive bookmark still works?!

Technical Note TN2063: Understanding and Debugging Kernel Panics

//developer.apple.com/library/archive/technotes/tn2063/_index.html

..A different idea you may have already tried:

Transcribed Instructions from Paper: how to..

'Reset the SMC on Mac desktop computers'

A printed screenshot used w/ G4 Mac mini 1.5.

So this is one way to start a partially failed Mac.

Follow these steps for iMac, Mac mini, MacPro, and Xserve.

1. Shut down the Mac.
2. Unplug the power cord.
3. Wait 15 seconds.
4. Plug the power cord back in.
5. Wait 5 seconds, then press the power button to turn on the Mac.

Another:

"Resetting NVRAM"

• Shut down your Mac.

• Locate the following keys on the (Apple) Keyboard: Command, Option, P, and R.

• Press and hold the Command-Option-P-R keys immediately after you hear the Startup Sound.

• Hold these keys until the computer restarts and you hear the startup sound for a Second time.

• Release the Keys.

(Some users found, listen -and- let 'Third

Chime' sound; be sure PRAM is cleared.)

•After resetting NVRAM, you may need to reconfigure settings for speaker volume,

screen resolution, startup disk selection, and time zone information."

..These 2 instructions are transcribed screenshot notes

'Late 2005 Mac mini 1.5GHz' last model w/ higher specs.

The web.archive was for Intel mac & PPC models

You could try replacing the clock battery.

With the Quadra 660av, if the clock battery died, then when you tried to start up the computer, you'd get no video.

Fans will ramp up for safety until the OS boors up to control them.

Sounds like the video card is bad.

Try aSafe Boot from the HD, (holding Shift key down at bootup).

Any video?