PowerBook G4 12" VRAM Oddity

timidpimpin

macrumors 6502
Original poster
Nov 10, 2018
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Cascadia
Hi,

I have a 12" PowerBook G4 (1.5GHz), and half the VRAM has suddenly gone missing. This model has a Geforce Go 5200 with 64MB, but that total is suddenly 32MB.

Nothing I have done would have caused this, as I didn't install any type of VRAM related software or utilities. I'm not using another monitor either... just the built in 12" LCD.

Any ideas?
 

timidpimpin

macrumors 6502
Original poster
Nov 10, 2018
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Cascadia
This has never happened to anyone else? It's the oddest thing that has happened to me on a Mac in my life. Literally half the VRAM just vanished one day. Everything is fine otherwise though. It still functions perfectly.
 

AphoticD

macrumors 68000
Feb 17, 2017
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Australia
It could be a kext cache issue. I have a G5 which occasionally loses USB functionality until I rebuild the cache; in my case I assume the hard drive is slowly failing.

In Terminal run;
sudo touch /System/Library/Extensions

In either Leopard or Tiger, this will force a rebuild of the extension cache on next boot, so reboot your Mac and let it load up again to see.

You could also try confirming using a different system, or even just boot from an OS X installer disc and run System Profiler from there.

If none of that points to 64MB then try a PMU reset, zap the PRAM and reset the NVRAM.

On a hardware level, VRAM failure is possible and given that these little powerbooks can trap a lot of heat, it would be likely your onboard GPU is on its way out.
 
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timidpimpin

macrumors 6502
Original poster
Nov 10, 2018
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Cascadia
I have zapped and cleared everything possible. Nothing... My best guess is a dead VRAM chip. I'm not sure of the board config, but I would guess the dedicated VRAM is either 4x16MB or 2x32MB chips, and half are likely dead.
 
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AphoticD

macrumors 68000
Feb 17, 2017
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2,188
Australia
I have zapped and cleared everything possible. Nothing... My best guess is a dead VRAM chip. I'm not sure of the board config, but I would guess the dedicated VRAM is either 4x16MB or 2x32MB chips, and half are likely dead.
That sounds very likely.

I’m not sure if it will reveal anything useful, but you could test the hardware using the appropriate AHT or ASD disc for your PowerBook.