Macintosh

[junsct]

Just 1 week ago, my imac g5 started acting strange.  It shuts down without warning.

I did some troubleshooting, and believe it is shutting down if the network cable is plugged into the computer.  If I take it out, the computer runs smoothly.  If I plug in the network cable, in less than 30 seconds the computer shuts down.

I took it to Best Buy and the apple store with my network cable, and both places came back and said there didn't seem to be anything wrong with it, even testing my cable. Diagnostics showed NIC is fine, and power settings.

Could there have been a firmware or software update to my cable modem that is causing these problems with my computer?

Can I get my modem reset or flashed? Or maybe it needs to be replaced...

FYI:  I am connected to the modem directly, I do not have a router

Thank you.

[Weil]

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junsct wrote:

Just 1 week ago, my imac g5 started acting strange.  It shuts down without warning.

I did some troubleshooting, and believe it is shutting down if the network cable is plugged into the computer.  If I take it out, the computer runs smoothly.  If I plug in the network cable, in less than 30 seconds the computer shuts down.

...

FYI:  I am connected to the modem directly, I do not have a router

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I suggest that if it works wirelessly, then buy a wireless router and use it.  This solves your problem directly and provides insurance against a lightning strike/power surge via the modem which has been known to happen.  (I also highly recommend a surge protector for your own equipment from the AC power.)

sam

[UHFhd]

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[Paraniod]

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UHFhd wrote:

HI 

     Is router rented from comcast or owned ? How old is router ? Is it in  list of approved modems? 

   or at end of life                                                                           http://mydeviceinfo.comcast.net/

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OP doesn't have a router....I think you meant modem...NM.

[UHFhd]

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[Paraniod]

Try swapping the cable from modem to mac, could be bad. Guess you tried unplugging the modem to reset it?

[UHFhd]

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[Paraniod]

Yeah, I know just saw that...!

[junsct]

Kernel Panics.... saw somewhere to reset PRAM.. apparently it will clear KP's.

I'm going to try wireless as well.  My neighbor has wireless, i can ask to join for testing. sure they won't mind.

[junsct]

Modem is rented, just got service in December.  Will check the modem for EOL

[UHFhd]

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[junsct]

Power settings are already set to never..

I did not repair permissions yet...

However, did get connected to my neighbors wireless, and system does not shut down.  I think for weirdness sake, I might just get the basic netgear wireless router, and be done with the ethernet connection.

[UHFhd]

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[BethKatz]

I don't like the idea of settling on a wireless router as a "solution". I agree that it avoids the physical connection, but it's often a slower connection. And you need to be sure to lock it down so that your neighbors don't use it without permission.

Crashing is not "going to sleep". Why are you plugging and unplugging your network cable?

Are you running any unusual kernal extensions? Did you install any new software a week ago? 

[rammas]

does this network cable happen to provide power over ethernet? if so then you might be experiencing power troubles.

[Weil]

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BethKatz wrote:

I don't like the idea of settling on a wireless router as a "solution". I agree that it avoids the physical connection, but it's often a slower connection. And you need to be sure to lock it down so that your neighbors don't use it without permission.

Crashing is not "going to sleep". Why are you plugging and unplugging your network cable?

Are you running any unusual kernal extensions? Did you install any new software a week ago? 

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An iMac g5 has at least an 802.11g wi-fi card.  I doubt that it would run much slower than the Comcast network.  As a $30 router solves a problem and eliminates multiple trips to repair shops which quickly add up to higher costs and waste invaluable time, I suggested a simple solution that resolves the problem.

A quote to consider:

"Would you tell me please, which way I ought to go from here?
That depends a good deal on where you want to get to, said the cat.
I don't much care where -, said Alice.
Then it doesn't matter which way you go, said the cat"

sam

[BethKatz]

I don't have a problem with wireless. I use a wireless router in my house, but some machines are wired.

But while that works around the immediate symptoms, is there something else going on that caused the problem?

[Barmar]

Could you provide more details about what happens? Your subject line says "sleep", but the message said "shuts down". Do you get a kernel panic message when this happens? This is where the screen turns dark and says "You need to restart your computer. Hold down the Power button for several seconds or press the Restart button."

If the computer just loses power totally, as if you'd pulled the plug, I suspect some kind of short circuit on the processor board, so that the NIC is somehow connected with the power supply.

[Weil]

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Barmar wrote:

Could you provide more details about what happens? Your subject line says "sleep", but the message said "shuts down". Do you get a kernel panic message when this happens? This is where the screen turns dark and says "You need to restart your computer. Hold down the Power button for several seconds or press the Restart button."

If the computer just loses power totally, as if you'd pulled the plug, I suspect some kind of short circuit on the processor board, so that the NIC is somehow connected with the power supply.

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The ethernet circuit/chip should be completely separate from the wi-fi card and therefore your conjecture concerning this failure possibility is potentially correct.  A new processor board might cost more than a new computer as I assume that this is an old machine.  As usual, I assume that all of us recommend a complete backup of all user files be maintained.  An external portable usb hard drive of sufficient size costs about the same as a router.  With no huge music or video files, a small usb2 keychain drive would work.

sam

[Barmar]

The really confusing thing is that he said they couldn't reproduce it at the Apple store. If there really were a short circuit, it seems like it should fail for them as well.

This suggests something specific to his cable modem. If it's old, maybe it's gone bad and is transmitting a bad signal.

[Paraniod]

I'm with Barmar, wouldn't hurt to swap the modem out, just to see.

[beneshelman]

Was the issue with your iMac G5 ever resolved?

I'm a Mac Technician and have long experience with computers like yours so I was curious about your issue.

Shut downs on G5 iMacs are most often related to failing power supplies, however your description leads me to think that there is a short circuit in your modem.

Connecting to ethernet does not usually bring a weak power supply down; processor-intensive tasks are usually the cause.