> [...] allows to use PMacs with only one CPU [...] (needs less energy,
> produces less heat (also on NorthBridge) and you can safe 1 CPU for spare.

...or simply use MorphOS 3.10 or newer, which disables the unused CPU ;-)

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=11&topic_id=9353&start=25

No, not really - idling CPU nevertheless consumes energy (gets warm and can measure more energy consumtion - about 50-60[W]). And as a interessting side effect: If 2nd CPU is installed, also Northbridge gets much hotter, whether CPU is idling or not.
I tried to kill 1 CPU in OpenFirmware - but makes no difference.
I've seen this behaviour on my 1.8GHz and on 2.3 GHz, which has an older motherbord from a 1.8GHz machine (yes, that works too! FSB goes up form 800MHz to 1,15GHz)
My newer 2.0 GHz and 2nd 2.3GHz won't work with only one CPU.

>> ...or simply use MorphOS 3.10 or newer, which disables the unused CPU ;-)

> No, not really - idling CPU nevertheless consumes energy

Yes, an idling CPU consumes energy, of course, but as far as I understand, a disabled CPU is disabled, not idling. If you say "disabled" means idling, then what did the 2nd CPU do from MorphOS 3.2, which introduced G5 support, through MorphOS 3.9? What's the difference regarding the 2nd G5 CPU between MorphOS 3.2-3.9 and MorphOS 3.10-3.17? If it's simply idling like before, then what's the point in having it disabled since MorphOS 3.10?

> I tried to kill 1 CPU in OpenFirmware - but makes no difference.

Yes, this was discussed in the linked thread. Setting the "boot-args" variable in OpenFirmware to "cpus=1" is not affecting OpenFirmware itself but just Mac OS X.

As others have recommended the 2.3 is probably the best for just getting going. You still may want to pull the heatsinks and give in a good cleaning and put new silver on the CPU.

If you are handy, you can get either the 2.7 (Dual Core) or 2.5 (Quad Core). It will make a difference if you want to play videos with playback. My 2.7 is noticeably faster than my 2.3 with playing HD content. Get a fast card like a 1950 that also helps. You should pick up a donor 2.0 system to move the heatsinks over and delete the liquid cooling. I just did mine based on the videos and it worked perfectly.

The speed of these systems is really impressive. Good luck!

All I can say is, after installing MOS 3.10 (? I think it was 3.10...), that CPU 2 always runs about 20°C lower then CPU 1. Before both CPUs always had nearly same temperature (+/- 2°C)

To come back to Templarios question: In my opinion you can take any type of G5. It doesn't make a huge difference in every day use. Even Wayfarer isn't noticable slower on a1.8GHz (compared to 2.3GHz).
If you really need CPU-power for extensive application, take the 2.7GHz-version or 2.3GHz version to prevent all troubles with watercooling.
Be sure, that there is a supported grafic-card (Radeon!) built in. Take a look at MOS hardwarecompatibilitylist.

> CPU 2 always runs about 20°C lower then CPU 1.
> Before both CPUs always had nearly same temperature

So when unused/idling CPU 2 had the same temperature as used CPU 1, how can CPU 2 still be simply idling as before and being significantly cooler at the same time? This doesn't make sense to me. Anyway, I'll ask for details in the other thread in the hope that the MorphOS team will clarify that note found in the MorphOS 3.10 release notes.

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Thank you for your information, I don't know these different CPUs.

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I would say go for the not 100% supported PowerMac G5 11,2. You will have less headache using newer GFX Cards. I switched from an aircooled G5 2,7ghz to an G5 Quad with 2,5 Ghz with PCI-e and have a Radeon 4550 installed. So i can use the HDMI Port to connect my ultrawide 34" 3440x1440p Monitor to use the full resolution. And afaik the DDR2 Ram will speed Wayfarer and MPlayer up.

The PCIe G5 is great, but has two caveats:

- You need a PCIE RTL network card since we have no support for the dual network chip that comes with this model
- You need to keep the NVidia card around (best inside if you happen to have the single slot card) since that's the only way to access OpenFirmware, unless you are lucky enough to find an Apple X1950 card (rare and expensive).

[ Edited by jacadcaps 11.11.2022 - 15:01 ]

> Apple X1950 card (rare and expensive)

That would be X1900 GT. I remember reports of cheap AtomBIOS Radeon X19x0 cards working with OS X and OpenFirmware when flashed with the PPC ROM of the Apple X1900 GT.

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It's extremely important that you go to the hardware compatibility page the only version of the G5 that is fully supported is the 7,2 version and it must have a Radeon card for graphics.

I've personally found that the intended boot hard drive must be in the connector associated with the lower position.

> go to the hardware compatibility page the only version of the G5
> that is fully supported is the 7,2 version

"Only PowerMac 7,2 and PowerMac7,3 (A1047) are fully supported." (emphasis mine)
https://www.morphos-team.net/hardware

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I have already purchased the PowerMac G5 to play and surf the internet.
Now waiting in a next MorphOS gives support to dual core and the 4GB of memory.