Hello,

I've tried to fix my old G5 (DP 2 GHz PCI-X)

https://everymac.com/systems/apple/powermac_g5/specs/powermac_g5_2.0_dp.html

It was on my attic for some years now, and recently I tried to make it work again. The PSU was broken, so I swapped it with one from another broken G5, and now I've got the problem, that it still doesn't start. The PowerLED blinks 3 times, and the posts on the internet say that this is a RAM issue. Well, I swapped various RAM sticks in the correct order, took different RAM of the same type. But the error still occurs. Is there the possibility that some other things are broken? I resetted the SMC (or PMU), too. No change.

Just to be sure, you placed the RAM sticks really in the correct way, as described in the manual, not the way one would think it has to be done?

The correct way is:

4
3
2
1

1
2
3
4

Right? This is the way I put them back.

Memory controller, perhaps?

@analogkit
yes.

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Hmm, is there a way to find out more details?

I had the same thing on the G5 1.8 single cpu. I tried to change the memory sticks, but in the end the memory slots or the memory controller were bad. (I don't know exactly)
I found the most probable reason on the Internet - microcracks in the soldering of those slots. Also instructions on how to fix it with hot air, or baking in the oven. !! # @
I was already so desperate that I bought a hair dryer (I'm bald) and heated the board in the place where the memory slots are for about 10 minutes.
G5 really started working, but only for a week and then G5 boot only randomly and I finally bought another G5.
Theoretically, it could be fixed, but I don't have the right tools.

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You've got 8 memory slots. Try putting a pair of RAM sticks that are surely good in just one pair of slots (1-1, 2-2, 3-3, 4-4). If that doesn't help I think we can rule out the bad solder joints on memory slots. That would suggest it's the memory controller fault. Sadly, it's located on the other side of the motherboard. If you did change the thermal paste and refurbished id properly then maybe - as a last resort solution - you could treat it with some hot air and see if this helps?

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Thanks for that suggestion. I tried putting a pair of sticks in the two according RAM slots, but this didn't help. I'll disassemble the machine and look closer at the memory controller.

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How did it go?
I have almost the same problem on my dual 2.0 and I'm curious to know if you succeded to repair your G5.

What DIMMs did you install? Do you have 4 or 8 sockets? Do you here the normal startup-chime?
4 sockets machines: minimum PC2700
8 sockets machines: minimum PC3200
Models till june_2004/early 2005 supports only 184Pin/2,5V DDR400-compliant DRAM SIMMs (=PC3200)

If you use PC2100, startup-chime is 3 single tones and front-LED flashes 3 times.
If SIMMs are not or not correctly installed (mechanical, etc.) you hear a single tone and front-LED flashes every 5 sec.



[ Editiert durch Amigaharry2 10.01.2021 - 09:40 ]

The G5 is a early 2005 dual 2.0 and it worked til I dismounted processor units to clean dust on heatsinks.
When I reseated the two units, G5 didn't work anymore.
Memories are pc3200 and they worked (it's my only G5 machine with MorphOS registered) and it is a 8 sockets unit. No startup chime at all: it power on and stay there, no blinking lights, no chime.
Two days ago, the G5 didn't power on and I guessed it was gone. I put inside the power supply of my early 2005 dual 2.7 (checked voltage specs and are identical) and it powere on but it stays as I described above.
There is another mistery, related to dual 2.7 I started to restore: since it didn't start anymore (power on but no chimes and fans at maximum speed) I bought a logic board and changed. Machine starts, no startup chime, no fans at maximum but three blinking although I am using PC3200 units. If I let the G5 start without DRAMs, no chimes and a single blinking light every three seconds correctly because it doesn't find any DRAM.


[ Edited by Jambalah 10.01.2021 - 09:48 ]

Personally, I try to limit the work I do on my G5's (both watercooled and a PITA).
The developers might be willing to issue you a key for a replacement system (and they're relatively cheap).
That would give you a known good system to test your memory in.

For Powermacs G5 you can try to boot with only one cpu at time.

In your maintenance disassembly/reassembly you can have damaged something like cpu socket/cpu board.
Be sure your cpu is in full contact with its heatsink.

I have rebuilded from scratch G5 quad LCS with custom parts, I know manage powermac parts is not a joke, it's completely different beast, not sure an usual pc.

Try also to reset pmu and spu and change cr2032 battery.

@Jim:
I guess it is what I'm going to do. I have no time to investigate inside G5 to discover something I dom't really know. Funny... I tried to power on the MDD and it's acting crazy, booting one time to five attempts. Junkyard is ever closer...

@Flash:
I checked the cpu sockets and I found no damages. I will check again. The heatsinks are ok, cpu is in full contact with them.
Resetted pmu and spu and changed battery with another one working: didn't work.

Thanks for tips to you all!

Only G5 with older Firmware (til june 2004,1.8GHz) will boot with only 1 CPU (in upper slot) -all later versions needs both CPUs.

@jambalah:
Seems that you have shot one or both CPUs - can be a mechanical crack during remounting. I can only suggest, that these CPUs never (!) should touched, as long as they are running flawless.
Are you sure that all pins (cpu-socket) are ok and not bend? Do you have other CPUs to test?


These early checkings (RAM, etc.) are not done by CPU, but from logic-boards on-board-logic. After all this low-level-tests CPU is initialized at last. If everything is OK and CPUs works, the normal startup-chime will confirm that and system boots to OF.

I have tested on my powermac g5 quad (late2005) it runs ok even with only one cpu (dual core)
Meanwhile I was rebuilding LCS from scratch, I used it with only a cpu module and passive “big” heatsink taken from another powermac.
Anyway don’t touch them if really not necessary..

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No luck. I bought a replacement machine together with a TFT Studio Display, and I'm using the 9600 (with ADC) from the dead G5 in this. because the two cards which came with the "new machine" are a Geforce and a 9600 without ADC. I'll take the rest of the old G5 as spare parts.



[ Edited by analogkid 10.01.2021 - 17:09 ]

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A Quad-G5 (2xCPU each 2 Cores) is not the same as a Dual-CPU-G5.

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Sorry to read this but happy you solved.
I'm still working on my dual 2.0 but I discovered what it was supposed some post before and I didn't noticed well: some cpu pins are bended and I guess this happened because the bumpers on the rear were unglued. Anyway it went, I found a motherboard at ridicolous price and I changed but i discovered from codes this is was a dual 1.8 G5. Could it be a problem? I changed thermal past to the rear heatsinks and so I did for the cpus, I reseated with as much care as I could and I powered on: G5 started but no chimes and three blinks. Changed slots using the second one in pair and started again: no chimes, fans started to run higher speed but MorphOS did the boot!
I was at 3.12 version of MorphOS and I tried OWB but no internet though G5 was connected with cable.
I booted diagnostic 2.5.8 cd and started calibration: program found intake cpu fans not calibrated but after calibration it still warning error for those two fans. I checked fans diagnostic and this passed. Tried calibration again but errors were still there.
So I'm thinking if the motherboard could be the problem due to different cpus that were mounted onboard.
Cpus temperature under MorphOS doesn't go over 23° Celsius.
I forgot to mention that even though i have two 512 mb simms, at bootscreen MorphOS display 492 mb. I will change the slots next check. i did memtest on mac diagnostic and it passed for both memory banks.

If you can boot to Open Firmware CPU(s) are recognized and OK. OF of 1.8GHz - mainboard is capable to handle 2.0GHz CPUs. Have the same config here (runs with 2.0GHz but at moment with 1.8GHz).
Netproblems are not caused by CPUs. That can be veryfied in OF. OF can handle TELNET and TFTP.

Type in OF to launch a Telnet-server:

Code:

where 0.0.0.0 is the IP of your MAC in your home-net.

Now you have TELNET access from another PC to this address (eg from Amiga or other MOS-machine from shell:

Code:

If you type in different OF-commands and get a reaction, then network-hardware is OK.

To check it you may also boot MacOS.

Fans: Check the connector of your intake-fans. Seems that Mac does'nt get back revolution-signal of fans, so it turns it to maximum (emercency mode). In worst case main-board is faulty. But in that case you can install a small PWM-contoller for manual adjustment in conjunction with PowerMac7FanControl (small DOS-Prog for MOS which can show cpu-temperature, and something more...). I have those problems at drive-bay-fan and backside-fan - they were allways running at maximum - like a jetplane.
If this is the case -> PM to me.

[ Editiert durch Amigaharry2 22.01.2021 - 20:17 ]

Thanks for the tips! I'm going to check. Update sooner...

Update:
I changed the intake cpu fans unit and restart calibration:
cpu 0 passed cpu1 failed with a change cpu unit error.
Restarted with MorphOS: no chimes but no fans speed up, fans are running quiet and cpu temperatures are changing between 52/55 grades C.
Network problem solved: the cable connected to G5 was disconnected on the router, my fault.
Battery is gone and I'm going to change since I had another one new and increasing ram with two pair of 512.

I'm going to install 3.15 and ask fr a license transfer =)

Thanks to you all for the tips!

Have you tested CPU in MacOS? Is there also only one CPU found?
In that case OF of your G5 (most of the 1.8GHz-versions), allows you to run with only one CPU in above slot. Second CPU can be completely removed. Even MacOS runs with only one CPU.

Startup-Chime: Sure, that the internal Speaker works? In MOS-Soundprefs you will find a slider for adjusting loudness of startup-tone - maybe it's turned off.


[ Editiert durch Amigaharry2 23.01.2021 - 10:02 ]