PowerMac G5 boot problems?

When the machine was in OS X I attempted to start installing Leopard, after restart the machine attempted to boot from the disc, the wheel was spinning for some time and then KP. After that no succesful boot, the machine tries to boot from the DVD first, when I did unplug the drive there was a question mark symbol for some time. I will now test if the machine forgets boot settings because as far as I know that is one of PRAM's work, I have unplugged power cord. If the machine attempts to boot from the DVD when I replug the power cord and boot the machine, then it wont probably be the battery but instead, the motherboard 😟

Still I will test with new battery. If that does not work, I will take a look at the power supply and procesors (if possible) and if those wont help I probably will remove motherboard and see if there is any visible damage to be seen.

The machine seems to like to cold boot instead of warm boot, that is obvious. These G5 machines are crap, I previously had iMac which I ended up repairing myself, bad caps and now this. Many Apple products have well known defects here and there, what makes things worse compared to PC's is that you cannot find spare parts that easily, of course if you are not experienced in building computers it may not matter, but for me it does. When my PC's MB failed, I ordered new one and after couple days the comp was up and running, cost me 40 euros inlcuding shipping costs, now if the MB is broken and cannot be repaired, that's it, I wont buy new MB with those ridiculous prices they are sold.

Message was edited by: thewk

Message was edited by: thewk

Message was edited by: thewk

Machine was unplugged for a while, and when I powered it up it still tried to boot from CD 😟

It is also notable that the "reset-all" command in Open Firmware does not reboot the machine but instead causes it to freeze, just like mentioned here:

http://forums.macworld.com/index.php?/topic/103827-power-mac-g5-logic-board-fail ure/

He tried new battery but with no change.

Message was edited by: thewk

Message was edited by: thewk

Yeah I have done all basic resets you can think of and those have no significant effect, however I noticed yesterday that someone nearby is selling working power supply in a local auction with a very reasonable price so I might buy it and see if it cures the problem.

Bottom line is that my PowerMac G5 usually works without any problems once you can get it to boot, I have surfed around the web, done benchmark such as Xbench and the machine passes them but then in very strange situations it hangs and booting after that is basically impossible. According to temperature monitor all values are normal (altough I still think nearly 70C degrees is much for any kind of chip, in this case memory controller.

It could very well be the power supply then, because the machine usually boots after I leave it unplugged for some time. Maybe it its the power supply which is overheating and causing these symptoms. Or the PRAM-battery which I have no received yet.

But still, I think when comparing to for example these PowerBook -machines, I use G4 at the moment, all G5's are technically much poorer and the G5 processor itself generates lots of heat and it is no suprise that Apple did seek alternatives.

Little update: I now have Apple Service Diagnostic -disc which I suppose includes other tests than the usual AHT disc does. The machine passes all of these also... weird.

More update: Replacement battery has not yet arrived, however I made strange discovery. I booted up the machine succesfully to OS X and immediately started running Cinebench ja Geekbench on the background, putting some stress to machine while at the same time browsing internet. This way machine was completedly stable for about two hours, all that time Geekbench ja Cine were running at the background. After two hours I closed those programs and continued to surf the web, I could only surf couple seconds when the machine froze!

My machine is more stable under stress than idle / low system usage.

Message was edited by: thewk

Hmm, I don't remember which setting I had, I have tried different settings before and I don't recall that changing the setting alone helped, but running those benchmark clearly made the computer to work stable much longer than it usually does.

I will test more when I have changed the battery but so far it is stange, usually computers hang under load than when idling.

I ended up testing without new battery, I had the setting "Automatic". I will do the same thing now, run those benchmarks on the background, if it runs solid again for couple hours maybe there is a power issue, when the machine panics it always says something about CPU1 so maybe it is defective, if not completedly then partially and it cannot run with lower voltages than max. or something.

"About my Mac" my shows that the are two CPUs as supposed to and all benchmarks have expected results for this kind of system.

Message was edited by: thewk

Today the machine worked 3 hours solid when I managed to get it to boot, this time I did not run benchmarks all the time, I did run them couple times in the beginning and then just regular web surfing. Processor performance was set to Highest and I disabled NAP via CHUD Tools. 3 hours and then I powered down the machine. No new battery yet.

It is very weird but the machine has gotten much more stable all the time during my testing and troubleshooting, 3 hours is the maximum time I have used this (I bought this used and got this machine extremely cheap because previous owner had these problems with it). When I got this machine it would take several attempts to even start the boot process, now it starts much more often.

Message was edited by: thewk

Hmm, I'm not sure if I understand what that means, you mean that there are bad joints on my motherboard and putting maximum stress sort of creates proper electronic flow or something? Sorry my native language is not english 🙂

I forgot to mention that I downloaded a demo of Halo and tried playing it, no problems with that either.

I'm pretty confident that the problems with this machine are caused by either failing motherboard or processor. I booted up the machine and started Cinebench with multi-CPU rendering. Suddenly the mouse froze and I thought that okay, I need to restart the machine. However I noticed that the rendering process did not stop completedly, the other processor kept rendering! During the start Cinebench divides the output picture 50/50 and half of the picture was succesfully rendered.

I guess I should try removing and reattaching the CPU.

Message was edited by: thewk