I think maybe the air cooling just isn't as effective as water cooling for the 2.7Ghz, hence the fans need to spin up to keep it cool.

Btw. my 2.5 also sits at +-160f ( 71c ) all the time.

The difference is no matter what I throw at it it doesn't rise or the fans spin up. I have left MDW's demos on loop for hours and the CPU is pegged at 100% and it doesn't rise.

How about fine-tuning fan speeds with the PowerMac7FanControl command, if you dare?

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Hmmm.

I have 2 options it appears.

1. I play with the fan speed as described in the link and hope to guess it right. It hovers around 170F so I'm worried I would cook it.

2. Put all Noctua fans in the box and lock it at the maximum spin which is 2000 rpm for the best model for the job and hope that a constant 2000 is going to keep everything cool enough.

I'm leaning on risking the second option, it seems safer to me.

Any thoughts before I pull the trigger?

170F should be just fine. Generally up to 85C is safe, even if it’d temporarily go to lower 90s (just as long as it doesn’t stay there).

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Matt, are you sure you didn't replace the fans with the wrong type? A DC fan getting a PWM signal would spin at nearly full speed all of the time. A PWM fan getting a DC signal would spin at full and turn itself off early, causing heat to build up that would then require it going to full. Either isn't good.

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Not sure that's possible. The PM fans are indeed both RPM and PWM controlled, but there don't seem to be differences between PMac models in this regard. As in: an RPM controlled fan will be RPM controlled in all models.

As for Noctua fans: matt, are you able to get Noctua fans built FOR the PMac? The connectors on PowerMac fans may look standard, but the voltages are NOT. You WILL burn your PMac if you mess this up.

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Am I sure? No not one bit:). These don't seem to be built for mac...

I was going to get a NF-A9 PWM that run at 2000RPM, from the graph on the website it is the best all around for air movement and pressure, that I didn't even know there was a difference before I went to the site.

I was going to wire them for max speed and just hope for the best. I suppose there has to be a way to get a reading and see if that is reasonable?

I did put one Nactua fan in as a test to replace the fan by the speaker. I wired it to run contstant. So far so good. This fan doesn't impact the cpus that much but was a test case...

[ Edited by matt3 28.01.2023 - 11:17 ]

Tried playing with cpu temp by setting it to 80c and nothing changes. The Fan most of the time are running at 2000rpm and are loud. Weird that the temp is 168f and it still spins about 200 rpm faster when it never did in the past.

A quick update to help someone to not loose sanity :).

I quickly cleaned up the liquid cooling unit and put it back in to compare against the heatsinks.

They run exactly the same for temperature and the fan noise is still just as loud.

So here is what I suspect:
1. My room is a bit warmer in the winter time and in the summer time I have a AC that keeps it cooler and makes it less of an issue. (I will test this for sure in the summer months).
2. The 2.7 just runs hot, so no matter what you do it will be tough to handle. I will be testing the 2.0 PCIe soon and I will see how loud it is.

Perhaps someday, MorphOS will better handle the fans in the powermac series.

MorphOS handles fans well - i've 4 PMG5 (1,8-2,3GHz) all running very silent. (CPU ~ 55-65°C).
Only one G5/2GHz sometimes backsideblower (cooles Nrthbridge) becomes loud, but not often.

This seems to be a problem of your PM. If nothing changes by setting different CPU-temps (PowerMac7FanControl), then there is something wrong with fan control on your board (or fans). Every PM I've seen, reacts to different temp-settings (incuding 2.7GHz-watercooled G5)

Are you sure, the loud noise is'nt comeing from backsideblower?

Matt,

Here is a pretty good thread on converting the fans to standard PC versions. Its not perfect, but it helps some. The 2nd link is a bit more info.

https://68kmla.org/bb/index.php?threads/whats-the-deal-with-the-fans-in-powermac-g5s-a-call-to-electronics-experts-for-help-with-retrofitting-fans.37489/

https://www.tonymacx86.com/threads/info-on-g5-fans.69889/

[ Edited by Acill 12.03.2023 - 06:31 ]

Well good news.

I finally got the 2.0 PCIe system running and it is now decent for fan noise! (Big thank you to Frank for all the help!).

The temp hangs around 115F now, a big different from the 2.7.

I will replace the fans like Acill said eventually and see if the 2.7 can be made quieter.

It is good to know for everyone that air cooling produces the exact same temperatures as liquid cooling.

[ Edited by matt3 13.03.2023 - 15:45 ]