G5 Dual processor is now a single processor.... hmmmm.

[Schmoburger]

So, I just booted up my clapped out and flakey Dual 2.0 G5 which works sometimes when it feels like it, and it is for the moment, running without a glitch... I am actually posting this from it using shared-screen being that it has the studio display attached and the Dual-Core does not, and I miss the big screen. Anyway, I digress.

The only problem is that whilst it is running without a glitch, it is running without a glitch seemingly off only a single CPU, with System Profiler registering that there is a single 2.0GHz G5 processor in it. Now, I've been chasing freezes, boot failures, finicky RAM issues, KP's and wierd fan behaviour for some time hence why I retired the machine in  and replaced it with the late-2005 G5 in the first place. I had put this insufferable unreliability down to flakey soldered connections in the RAM bus circuitry as this has been one of many known problems with early G5 towers for over 10 years now. However now that I notice this AWOL CPU, I am wondering if perhaps the issue is possibly a more likely to be a failure of the CPU itself, which would certainly be a whole lot easier to replace than removing and reflowing a logic-board.

What are peoples thoughts on this latest development?

 

[TheWhiteFalcon]

Happens.

A friend has several of these. He picked up a 2.3DC with a bad psu, which sat until he picked up a 2.0DC that was fine.

Of course, he wanted to fix the 2.3, so he swapped PSU's and parts.

The result? The 2.3 CPU only works with the board that was in the 2.0. It won't work with the board that it originally came with. And right now you're thinking bad LB, right? Except the 2.3 board works fine with the 2.0 CPU.

Explain that, lol. These things are just finicky beasts in general.

In short, I'd pull the second CPU (if its not the top one, put the good one as the top one or it wont run) and run it as a 2.0SP for a while. If it holds up, then consider a CPU replacement if the machine warrants it.

You could also try a processor reseat.

 

[Schmoburger]

Hmmmm sounds good to me. :0 So I guess it'd be fairly safe to assume that if it will not run without the top CPU, then it is probably the bottom one that is likely to be bad if any  anyway? I am still typing this on the half a dual-processor machine after about an hour of running without a recognised second CPU... same session, no reboots or freezes,, that said I switched it also to running at reduced-rate. There is some occasional fan spool-ups and I don't have temp monitor on this machine to suss out what it's doing, but It isnt going nuts and trying to take off from under the bench yet.

I really would like to keep this machine running in some way or another as it seems a waste using it to grate cheese when sometimes it works stirlingly.

 

[TheWhiteFalcon]

When I mentioned the top CPU, it's that the system won't boot if that slot isnt filled. It's likely the bottom unit that's failing anyway since it is working.

 

[Schmoburger]

just restarted to set boot arguments to only run one CPU... now the mongrel hangs just before the login screen.

 

[Macdrone]

Boot using Apple diagnostic Tools, the same disk for resetting the fans and you can do processor tests and it will tell you which one is toast (if you get it to boot).  My dual 2.0 would not boot and it was the main proc that was faulty.  I switched them, let the fans run on high and confirmed.  Then bought a new set ( one of those was dead) which was ok as I only needed 1.  Then reset the fans and was rock solid ever since.

 

[Macdrone]

Be careful, when getting a replacement CPU you have to get the matching series or set.  I bought a wrong series and it would not work on the motherboard. First series 2.0 would not match with second series proc.  Has to be matched series.

 

[Schmoburger]

Sounds good. I had the thing running stable for about 4 hours after my last post here, with all subsequent post here and elsewhere being done on it via remote desktop. behaved itself all the way up to me shutting it down for the morning, and now seems to be booting day two in a row. It almost seems as though the processor was flakey but has now just gone AWOL to the point where the computer isnt even recognising it anymore and by not negotiating it, is not causing problems... seems half feasible

.

 

[Schmoburger]

Update: Just booted to OF after a hang and failed boot at the spinning flower, once again set boot args to use 1 CPU only, and it booted up quicker than it ever has... think I may have found my problem for certain. bad #2 CPU.

 

[Schmoburger]

OK... further update. looks like for some reason it just reverted back to running two CPU's... so back to square one.

However with iStat Pro running, I am seing a consistant variance of 8-10 degrees celcius at close to idle with fairly even usage between CPU's. Only idling at 40-50 degrees but I am about to load it up and see what kind of temps I push from both.

 

[johnklos]

Did you reapply heat sink compound? Sounds like it may be inconsistent cooling.

 

[Macdrone]

Unless you disable or pull the bad cpu it will always try and find it. When it does you get issues.

I think with the apple hardware disk you can disable it that way. Or again just pull the offending fpu and re set the fan control. Either way you need ASD 2.5.8.

 

[Schmoburger]

Where does one obtain this DIags disk?

 

[Schmoburger]

Well I just the machine a clobbering for a bit... Recording in Garageband, whilst running repeated XBench passes, with Google Earth open, Itunes playing music, windowed with visualiser, Mactubes playing a video, as well as launching various programs like iPhoto, iDVD and iMovie, with CPU monitor running, an idiotic screenshare video-loop happening on both G5's, Energy saver CPU setting set to full noise. Still a decent gap, of at least 6-8 degreees but couldnt crack anymore than 60 on the hottest CPU (A) and it didnt freeze. Killed the dual-core off to bail out of screenshare as both machines were choking on it, dual-processor was running around 97% both sides, and then killed off all the other processes and let it all simmer back down.... now it's just locked up  with CPU A at 52 deg and CPU B at 44 deg, which to me seems like nothing given my dual-core will sometimes get up to 72 degrees and not have any problems....

I also note however that at the point of lockup, the in and out fans for CPU B were only running at just over 1000rpm, whereas the CPU A fans were cracking over 1400rpm.

 

[Schmoburger]

OK, so I let the machine cool down  and then booted into OF, this time got it to maintain the bootarg setting and boot with only one CPU. Performed the same test as before on a single CPU, loading it up to 100% usage constantly for twice as long as last time and it remained stable and temperature stayed fairly even, even whilst choking on the workload I threw at it. Not a whole lot of fan activity either. I have since closed everything down except one video in QuickTime player, which I played through once more for 5 minutes and then let it come back to idle... still hasnt locked up yet and it's been about 90 minutes since I let it rest, with CPU activity at about 5-10%.

So yep, I beleive pulling the lower CPU might be the best option and then looking for a new set for a 7,3 model G5... and also this aforementioned diags disc!