machine shuts off half way when under load

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pry3i

chemical precursor
I've got an oddball for all you mac gurus out there. This problem has been plaguing me for a while now.

I have a Begie MT (gossamer) with 256mb ram , the factory compliment of peripherals and PCI cards - then added a Western Digital 60gig drive and a newer technology g4 500 zif.

So the problem is this - when I have the machine performing a task that makes it think pretty hard, the monitor goes blank - like it went to sleep
but pressing keys and jiggling the mouse does nothing.

my original thought was - damn aftermarket zif!. so i pulled it and put in the apple 266 zif only to find it made NO difference. it was still blanking. Hmm, well, how about - bad logic board. not too big of a deal and since I have a gossamer based power pc macine i built this past summer sitting at a friends house, i started moving the WD60 drive, the g4 500 ZIF, and the 256mb memory out of the apple into the built machine that WORKS.

well, the problem followed me to the built machine. so i pulled the 256 mb memory. no change. NOW the only piece of hardware that was present in either machine when it "blanks" is that WD60 drive.

This seems odd, but not impossible, i guess ... /var/log/system.log yields no clues. I cannot boot to single user mode to make changes to the file system... I wonder if its that Newer Tech ZIF...

Anyway- I am stumped and if anyone has seen this type of behavior before or has an idea on which way to procede, please let me know. Thanks.
 
Just out of curiosity, what are your energy saver settings set to? What happens if you set the machine to never sleep/never sleep the display?

Also, what graphics card do you have in the machine?
 
Does the machine startup ok?
Did you use the same clock battery when you switched machines?
Can you network the machines and see if it disconnects when the monitor goes blank?
 
El D - its not the energy settings. its the standard apple on board video.

Bobw -Yes startup is fine. if i do nothing with it it does not blank.
Each machine has its own clock battery and the batteries are ~8 months old.
I have not tried the machine networking technique. I will do so and leave another
reply.

I am still leaning toward the WD60 HD - I have physically eliminated all other hardware possibilities, but the network trick should provide more info...
 
I'm assuming that you're using Jaguar, since Panther isn't supported on that machine, right?

I'm leaning towards something with the on-board video -- have you tried removing some of the VRAM DIMMs or perhaps adding more? How much VRAM is installed in those machines?
 
Right. Jaguar it is. 10.2.8 . the Vram is maxed - 6mb (i think ... or maybe its 4)
The built machine functioned fine before I put the g4 500, the WD60 HD and the
256mb mem in it. I systematically removed the causes one by one. took out the
g4 500 upgrade, then the memory. so now the ONLY difference from the way it was
to the way it is, it the WD60 drive.

Just to re-cap. 2 machines - the apple and the built power PC . apple machine with all the components listed above would under some system load (i.e. CD burning, adding 6000 mp3's to iTunes library) would blank screen LIKE it had gone to sleep.
moved the components to the built power PC and the symptoms follow. Therefore it must be one of the moved components.

as you are aware, a large capacity drive must be partitioned with a maximum 8 gig slice for 10.n to reside on. I know it sounds weird, but I cant help thinking its this drive. I mis-spoke earlier the ZIF is not a newer tech, its a sonnet. I see by your sig
that you have one as well. do you ever have any problems with it?
 
No, I don't have a bit of trouble with it at all, but then again, it is installed in a different machine than yours, and mine came with a G4 ZIF to begin with -- so it's just a faster ZIF. Yours, on the other hand, I'm assuming, need drivers to function and what-not.

The only thing I can think of now is the hard drive, as you suspect. Check the jumpers and make sure they're on the master setting. Also, make sure the heatsink on the processor is seated correctly -- if possible, reseat it to make sure it has good contact with the processor. Your machine may be overheating -- symptoms of this would be a sudden shutdown, or even shutdown-like characteristics, like a blanking of the screen.
 
Sorry this took forever, but I can now answer bobw's question...

Can you network the machines and see if it disconnects when the monitor goes blank?
Click to expand...

the answer is NO - the machine does not disconnect.

AND i have ruled out the WD hard drive. I pulled it from the built system and its
STILL doing the weird screen blank out. The one thing that has occured to me (and
i dont know why it didnt sooner) is maybe the monitor has gone flaky. BUT you
would think that unplugging the monitor would be reset enough to get it back - but
the problem persists through the level 1 reset.

i'm at the point that i just want to get rid of these machines and start fresh with an
emac or something.
 
Do you have a different monitor that you can use to test it out? I have the same problem with a machine at work. Later this week, I will try the monitor on a different machine, then try a different monitor.
 
bobw said:
Monitor or video card bad.
Click to expand...

Dying monitor - the (new) direction i am leaning... the one oddity is that
when i reboot, the monitor comes back... unplugging/ powering off the
monitor does not reset it - the machine must be rebooted.

i cant imagine its the onboard video cause the same thing is happening on
two machines. my bad luck tends to be random - never that specific.

monitor it is. i will walk that path unitl i find out otherwise.

thanks bobw
 
Try zapping the parameter RAM. Also, when starting up in Mac OS X, press command-v, for verbose mode and try to read the text scrolling up the screen. Sometimes you can see errors, like hardware not matching up properly, etc... To set the computer to startup in verbose mode by default (it's not a permanent thing), login as root, and type "man nvram" in the Terminal. It will tell you how to set the verbose mode, something like "nvram=-v" or some variation of that. To get it back to normal booting, type "nvram=''" or some variation of that. Like I said, look at the parameter RAM and startup in verbose mode, a lot can be learned there.
 
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