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917Mhz from 1.25Mhz DUAL left. Is my G4 dead?

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paule:
Since 20 years my G4 Dual MDD (1.25Ghz) is running for music composing (Protools Mix 3) without any major problems on OS9.
But since two days I am fighting:
Symptoms. random freezing while or shortly after booting! and all of a sudden: CPU power lost!!! 917Mhz left!!!!!!
Already checked in a naked G4: software (system extensions) and hardware checked (RAM, Harddisks, USB Hubs).

I disconnected everything from the G4 and just started step by step. All of a sudden the system profiler tells me that my G4 Dual 1.25 has only 917Mhz left.

Can anyone imagine what could be the reason for that? Could this drop of CPU power and randomly freezes caused by a faulty Power Supply????

Thanks for any help,
paule.

smilesdavis:
yes reapply cooling paste. clean. reapply.

paule:
Hi,
thanks smilesdavis for the hint. I have ordered cooling paste. Let's see if it helps.
By the way: I found one culprit, which I have forgotten to disconnect: one of my dvd-superdrives causes the hangs when starting up, because its jumper aren't set to "cable select".
I have tested for hours now, but too many restarts also damaged at the end my startup disk. :-(
I am glad that I had a backup! :-) But at the moment the G4 is running better (but not perfect), but too crazy is, that the CPU is still only running on 917Mhz ... the same CPU rate you get when you start the G4 in "safe mode". But I am not in "safe mode" anymore and I don't know how to get out of it to get full speed 1.25GHz back. PMU reset and PRAM didn't help.

Best and thanks for any help,
paule.

GaryN:

--- Quote from: paule on August 17, 2022, 01:35:45 PM ---the CPU is still only running on 917Mhz ... the same CPU rate you get when you start the G4 in "safe mode". But I am not in "safe mode" anymore and I don't know how to get out of it to get full speed 1.25GHz back. PMU reset and PRAM didn't help.

--- End quote ---

I'll ask DieHard to confirm this, but I have never heard of the CPU(s) throttling down slower in Safe Startup Mode. AFAIK, Safe Mode disables certain Login Items, Extensions, dumps Font clutter and generally skips over everything not absolutely essential at Startup to prevent any of those from hanging up the process. Also, it's only applicable to OSX – the rough equivalent in OS9 is hold the Shift key for "Extensions OFF".

I'll make an educated guess here and suggest that maybe one (or more?) of the clockspeed-setting surface-mount resistors on the CPU daughterboard has come loose… possibly from the CPUs running hot for a looong time. I'm (again) guessing that after 20 years (!) without thermal paste renewal and (possibly) other deferred internal dust-out maintenance you have slowly cooked the daughterboard into… crispy-ness?

** Note: You didn't swap out the main fan at some point for something quieter and connect it to the same place as the original, did you? That is a certain way to cause the procs to run hot – ALL of the time.
Part of the problem is that there is simply no good temperature monitor for OS9 as in OSX. The only one that can possibly work is in "Jeremy's Bundle"… a set of Control Strip Modules, one of which is a temp gauge. I'll note that it does NOT work on my MDD with a Sonnet hot rod CPU card and I honestly cannot remember if it did with the original CPUs. I think it did, but…

Again referring this to our resident computer hardware know-it-all genius DieHard, does this sound like a decent theory? The obvious test procedure is a CPU swap - I know, big help if you don't have another on hand - OR is there some/any other likely suspect?

DieHard:

--- Quote ---I'll make an educated guess here and suggest that maybe one (or more?) of the clockspeed-setting surface-mount resistors on the CPU daughterboard has come loose… possibly from the CPUs running hot for a looong time. I'm (again) guessing that after 20 years (!) without thermal paste renewal and (possibly) other deferred internal dust-out maintenance you have slowly cooked the daughterboard into… crispy-ness?
--- End quote ---

Yeah, I was leaning toward a CPU daughter board issue also.

If it was a logic board system bus speed issue, (like going form 167 to 133); the quick math would be:
1250 Mhz. (1.25 Ghz.) / 167 (bus speed) = 7.485 Multiplier
So... if it went to 133 Mhz... 133 X 7.485 = 995.5 Mhz, NOT the 917 reported, so my dear Watson the issue is in the CPU daughter-board

The 917Mhz. is a result of the following math (PLL Multiplier):
5.5 Multiplier X 166.66 (Bus) = 917 !

The stock setting for your 1.25 Ghz. should be (PLL Multiplier):
7.5 Multiplier X 166.66 (Bus) = 1249.95

See the Table here: (Posted by PT5)
http://macos9lives.com/smforum/index.php/topic,1652.0.html

This is Literally a single resister, PLL_CFG[0] that is now Open

0=Closed, 1 = Open

1250 Mhz (1.25 Ghz Stock)
PLL_EXT = 0 (resistor or bridged)
PLL_CFG[0] = 0 (resistor or bridged)
PLL_CFG[1] = 0 (resistor or bridged)
PLL_CFG[2] = 0 (resistor or bridged)
PLL_CFG[3] = 1 (no resistor or open)

917 Mhz (Special Setting)
PLL_EXT = 0 (resistor or bridged)
PLL_CFG[0] = 1 (resistor or bridged)
PLL_CFG[1] = 0 (resistor or bridged)
PLL_CFG[2] = 0 (resistor or bridged)
PLL_CFG[3] = 1 (no resistor or open)
 
Lastly, download and burn the MDD digs from our download section, and run extended tests

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