Need PowerMac G5 hardware issue experts.....

Discussion in 'PowerPC Macs' started by tggalindo, Apr 8, 2014.

  1. tggalindo, Apr 8, 2014
    Last edited: Apr 8, 2014

    tggalindo macrumors member

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    Apr 8, 2014
    #1
    Ok so i obtain 2 power mac g5's, 1 of them is a dual cpu 2.5ghz watercooled model, and the other a dual cpu 2.3ghz normal heatsink fan cooled.

    Now the issue with the watercooled one is according to previous owner sometimes it will boot up and sometimes not and when it did boot up to mac desktop randomly it will shutoff.

    The other g5 issue is it actually boots up like normal but just 1 cpu is running and working. Last night i pulled both heatsink/cpu combo, and then removed each heatsink assembly for the cpu and clean and put on fresh compound and put all back together but still shows 1 cpu core. Will a ASD disk fix the cpu issue or is that only for calibrating the fans? Anyone know whats up here, is it just a bad cpu, if so How to tell which one? Can I pull out the bad one and just leave 1 cpu and use it liek that?

    How about the other powermac issue? Bad motherboard and or powersupply?

    Another question can you swap the watercooled 2.5ghz cpu's into the 2.3ghz g5?

    Thanks
     
  2. gavinstubbs09 macrumors 65816

    gavinstubbs09

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    #2
    The LCS may be leaking, pull it and check. Random shutoffs mean it's overheating. It's a good idea to replace the O-Rings and flush the system. I did this with mine and it runs fine.
     
  3. tggalindo thread starter macrumors member

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    #3
    lol this sounds like im working on a car.

    Ok so pull out the lcs unit and check for leakage, if I dont see anytrhing how do you check if theres fluid in there, and what type of fluid gm dexcool? lol

    Thanks
     
  4. gavinstubbs09, Apr 8, 2014
    Last edited: Apr 8, 2014

    gavinstubbs09 macrumors 65816

    gavinstubbs09

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    #4
    It kinda is! Like mine refused to start yesterday although it had been off for over 20 hours. I pulled it apart and found it had a coolant clot! Something was completely blocking the flow through the water block. Only thing that is weird was it wouldn't boot right away, and there were 2 red LEDs on the CPU cards. Flushed the system and made sure no air was in the lines. Runs better than ever now! I removed the virus and it's no longer sick

    Dexcool sounds great! Actually I used Feser One but I'm sure you could just dump a gallon of water in it to keep it going! Kiddings :) Leaky cars are no fun

    The easiest way to check for coolant and drain most of it is to take off the CPU block. You can take off the hose at the top of the radiator, but don't cut it or anything unless you'll replace it. The fuel line (yes, FUEL line!) has a weird inside diameter. Fitting 3/8 on the fittings sucked, but it works.
     

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  5. Altemose macrumors G3

    Altemose

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    #5
    Do not swap any parts. We can probably get the 2.3 GHz going. Try swapping CPU A with CPU B and applying fresh paste. See if ASD 2.5.8 discovers it, and also zap the PRAM and NVRAM. For some reason I remember hearing of some people disabling one CPU in OpenFirmware.

    As for the coolant, you want some brand new coolant. Like a car, coolant generally lasts for 5-7 years unless you are a hard driver or had some substantial situation (leaks requiring mixing of new coolant, etc.). By a hard driver on a G5, I am talking consistent max CPU usage, like video editors. The last time I changed the coolant on mine, it was black from running a 45 minute video exporting. It started to heat very badly but the coolant was dried up and was pure black.
     
  6. tggalindo thread starter macrumors member

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    Apr 8, 2014
    #6
    OK just got here and read your post but already went ahead and ran this command in open firmware "setenv boot-args cpus=2" this disables the 2nd cpu right? which is the bottom one right? I ran asd 2.5.7 and that even sees the 1 cpu which is cpu0, thats before I did the "setenv boot-args cpus=2" command.

    Last night I didn't swap the cpu up and down I just removed everything and apply new compound and still reported just one cpu core cpu0. So you saying I should put the top one to bottom and bottom to top?

    If nothing else fixes the 21nd cpu from working is it a bad 2nd bottom cpu socket on the motherboard? Maybe like a xbox360 solder contacts are away from the circuit traces and not having a connection?

    I read another post where he did the cpu swap I believe and still only shows 1 cpu core so that told that the both cpus are good theres something up with the motherboard most likely.

    Thanks
     
  7. tggalindo, Apr 8, 2014
    Last edited: Apr 8, 2014

    tggalindo thread starter macrumors member

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    #7
    I did the reset button on the motherboard I think its called smu right there by the ram slots and now when booting up it goes to blank gray screen. You know a fix?

    Update: Never mind about the blank gray screen I guess, because when I went ahead and reseted the pmu switch and removed a aftermarket video card that was above the oem that came with the g5 and thats when it went to the blank gray screen.

    So i put that card back in and hit the pmu reset button again few times and now its booting up, So im thinking I did have the monitor plugged in to that other video card when i installed leopard fresh so maybe leopard was looking for and wanting the other card?

    So let me get this right this g5 has 2 separate physical cpus, one on top and bottom. the bottom will be cpu1 right? and top cpu0? So what is the proper open firmware commend to disable cpu1? thanks


    More question I see online a 2.3ghz cpu can be bought for 20 bucks, is this a option simply swapping in another one and its good to go? Probably have to run a fan calibration after to right? Thanks
     
  8. tggalindo thread starter macrumors member

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    Apr 8, 2014
    #8
    I ran the asd 2.5.8 disk to do the fan calibration and it failed at error cpu0 tafs is out of range.

    I did quick research and someone says the cpu is getting to hot to put better thermal grease. That might be the case because I didnt have the so called good thermal past like silver 5 if i remember right i have some generic crap and I notice when opening up a website and going to youtube the fan will speed up and down like the cpu is getting or already hotter than it should be. I'll buy better grease and see what happens.
     
  9. gavinstubbs09 macrumors 65816

    gavinstubbs09

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    #9
    The LCS one will rev the fans high for a sec opening a program, or on 24/7 watching YouTube. Mine does the same although annoying, even with a rebuilt LCS.
     
  10. Altemose macrumors G3

    Altemose

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    #10
    Always use a good thermal compound. What does Activity Monitor shown terms of processors? I believe there was a 2.3 single and a 2.3 Dual. The fans are normal.
     
  11. gavinstubbs09 macrumors 65816

    gavinstubbs09

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    #11
    2.3 single, early 05
    2.3 dual core, late 05 :)
     
  12. Altemose macrumors G3

    Altemose

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    #12

    So I did remember it right. That's good but doesn't help the OP any.
     
  13. Intell macrumors P6

    Intell

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    #13
    All 2.3Ghz G5 were two threaded. The non-late 2005 models are dual processor with the late-2005 being dual core.
     
  14. gavinstubbs09 macrumors 65816

    gavinstubbs09

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    #14
    He has a 2.3 ;)
     
  15. Altemose macrumors G3

    Altemose

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    #15
    So if its a dual core, it should only identify CPU0 but in Activity Monitor, it should show 2 "Processors" since OS X categorizes it by threads.
     
  16. Intell macrumors P6

    Intell

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    #16
    Yes, Activity Monitor shows thread count not physical CPUs. All 2.3Ghz G5's should show two CPU usage graphs. If it doesn't, then something is not working correctly.
     
  17. Altemose macrumors G3

    Altemose

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    #17
    Ah I see. Just out of curiosity, does your signature default to saying "Edited Yesterday"?
     
  18. Intell macrumors P6

    Intell

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    #18
    Signature? What signature? Yes it does. It comes in handy sometimes and it often tricks people. :D
     
  19. Altemose macrumors G3

    Altemose

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    #19
    Does a good job especially with the online indicator always off. :D
     
  20. tggalindo thread starter macrumors member

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    #20
    Speaking of dual core and such, yes it is a 2.3ghz g5, but do they really cally it dual core? Well I guess you can call it that, Im uuse in dealing with windows pc's like a intel or amd dual core cpu but its actually one physical cpu chip but has 2 cpus in the bigger cpu chip.

    But this 2.3ghz g5 I have its not like that, its actually 2 separate big ole heatsinks with the the 2 separate cpu's on each part.

    So is this called dual core?

    Today im going to put in better thermal compound on both cpus and see how it goes, can I swap cpu's from bottom to top? Does anyone know if the cpu0 which is #1 socket on top of the motherboard if it has a bad cpu the g5 wouldn't even start right? So if this is the case then if I sawp and it wont boot then that 2nd bottom cpu is bad right? Thanks
     
  21. Altemose macrumors G3

    Altemose

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    #21
    If the known good CPU (top) is put on the bottom and it works but the top doesn't then it is a classic CPU failure. If you put the top on the bottom and it doesn't work then you have a bad logic board.

    There are two types of G5s. One has dual CPUs, as in two physical processors. The other is a single processor with multiple cores (dual core).
     
  22. tggalindo thread starter macrumors member

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    Apr 8, 2014
    #22
    Yes ok so the 2.3 is dual cpu's as in two physical processors.

    A question.... the other g5 i have the liquid cool one 2.5ghz dual cpu's doesn't even work boot up, it turns on after few minutes the fans get faster but blank screen nothing. I see red lights inside the case if that means anything. So the 2.5ghz cpu's look the same physically and all to the 2.3ghz g5 so can i put the 2.5ghz's cpu's in the 2.3ghz g5? Thanks
     
  23. Altemose macrumors G3

    Altemose

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    #23
    The 2.5 GHz CPUs were liquid cooled for a reason. Is the clear acryllic door firmly and properly seated? Also is the liquid cooling leaking. Low coolant can cause it to heat and ramp up, but since the G5 doesn't get hot enough to burn the coolant it leaks out all over the joint.
     
  24. tggalindo thread starter macrumors member

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    #24
    I'll check that door I think it was closed though, is that a "no" in putting the 2.5 into the 2.3 g5?
     
  25. Altemose macrumors G3

    Altemose

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    #25
    Even if it would physically work, it would run way too hot. You would be surprised what 200 MHz can do for heat.
     

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