I have a G5 11,2 (2.0Ghz) that is my main MOS machine. I attempted to swap my X1600 GPU with an X1950 Pro and didn't have any luck with the 1950 after a few tries booting. After putting the X1600 back in, I noticed that with the clear panel removed, the fans did not spin up to full speed (with the red lights on) as usual.

Has anyone had this happen with their G5?

This X1950 is the first GPU I have tested that uses a power cable. I am worried that I could have possibly had a "bad" card affect something on the logic board when installing it.

Logic board reset did not solve this. Could it be a coincidental failure of the optical door switch?

And the bigger question: Why can't I stop tinkering with these machines when they work just fine??? : ) Ha!

-E-

Mine had a similar behavior (not sure if the cover detection ever triggered the fans) so it's not unusual.

Beware of anecdotal data as mine started flacking soon after and is now considered dead ;)

@EVX

We tinker because we can! :)

Would recommend you join the MorphOS Discord as that is where all the action is these days, and people have shared pictures of cards that work and ones that don't.

Did you use compressed air to see if there is something wedged in the slot tripping the sensor? I haven't seen that behavior myself.

Just make sure you unplug the PowerMac and make sure the flea light is off. Never pull the cards out and in with a charge on the board...

Your X1950 Pro likely works perfectly. If you just use the 1950 in the X16 slot, one in 5 or so attempts will bring it up fine off MorphOS, the 11,2 bios is funky without a PPC Bios video card. To make the 1950 work reliably every time... Put a Mac Bios Nvidia card in the 16X slot and the radeon in the X8 slot. Works perfect.

The only other option is to track down a PPC Bios 1900, that will run in the X16 slot just fine by itself. They are hard to find and MorphOS only sees 128mb of Vmem. For a one monitor system, no worries but if you are driving 2 monitors and have one above 1080p and the other at 1080p, you may run out of vmem and it will swap out creating minor slow downs as it happens.

MorphOS with the PC based 1900/1950 will see all 256mb vmem and that will never run out of vmem...

Also...

Pick up a 2.5 CPU and swap it in. Worth the speed! I might have a spare 2.0 or 2.3 lying around somewhere. 2.3 is still faster than 2.0 :). I would still track down a 2.5 if I were you. Runs cool with the heatsink and the speed is welcome.

A few videos out there showing how to do it. Chris Edwards has more than a few now on the 11,2 and MorphOS worth checking out...

Good luck!

Quote:

Back to anecdotal data, did that 6 months later I ended up with a dead PowerMac ....

I really should look into what failed one of these days.

@Kronos

I have 2 single processor powermacs 11,2 I swapped out years ago to 2.5GHz. No issues.

Chris Edwards and Acill also both swapped out their 11,2's to 2.5GHz processors as well with no issues.

I would be interested to see your findings with that, as it has been bullet proof here.

My main PowerMac 11,2 runs 8 hours a day all week and some on Saturdays and Sundays for a solid 3 years with no issues at all. Great system and very reliable. I have heard the QUAD's/Dual Processor systems seem to have issues because of the powersupply, motherboard, or liquid cooling.

The Dualcore/Single Processor systems seems very reliable and fast. I love mine... :)


[ Edited by matt3 21.03.2026 - 13:23 ]

Thanks for the input guys.

I have a pair of 7,3's @ 2.5 & 2.7 that each have a dead lower cpu from coolant corrosion. I've been tinkering with both of them and having no luck getting a chime. I am always an optimist so I think I'll get there one day. I sure wish these machines booted with a single processor installed and I would be off and running MOS already... I'm not sure I want to roll the $$$ dice on a quad to scavenge knowing what damage can be present on the 7,3 liquid cooled machines.

As for this G5 2.0, things seem okay for now so I suppose I will *try* not to worry about the change in behavior. I like the idea of tossing the NVIDIA in to aid in booting up with the 1950Pro.

Fun!

-E-

Quote:

Please, where is the sensor located?
I have also G5 quad ( buyed without plastic shield ) and it has cooling problems. And this looks like good chance to test it before I rebuild cooling system.

@sailor

I would suggest you watch Chris Edwards MorphOS videos on the PowerMac G5. He has around 10 of them now and in a few of them he discusses how the photo sensor works and shows you and even how to trick the sensor. Maybe in his Best MorphOS system there ever was on the PCIe Mac. All good videos regardless and worth watching.

In the picture below you can see the 3 tabs at the bottom of the clear plastic shield, notice the one tab that has a silver coating, that trips the sensor so the fans know it has the cover installed and run fans normally based upon the heat sensors. Without the cover the fans run in high speed. So the slit at the bottom furthest away from the front of the PM is where the sensor is.

PowerMac G5 cover.

[ Edited by matt3 22.03.2026 - 04:59 ]

@matt3
Thanks!

@EVX:
FYI

You can use the dual heatsinks from a Dual CPU PCIX 7,3 2.3GHz system on the 2.5 and 2.7 to replace the liquid cooling.

The PCIX systems had faulty liquid cooling, that can be rebuilt (recommend seeing Chris Edwards video where he rebuilds a liquid cooler for a 2.7 PCIX) The PCIe liquid coolers don't seem to leak nearly as much but the Quads can be problematic.

That is why to some in the MorphOS land, the best system to run MorphOS on is the PCIe single processor/dual core systems upgraded to a 2.5GHz cpu.. The 2.0/2.3 heatsinks on the 11,3 are just incredibly built and you don't have to worry about liquid cooling at that clock and since currently MorphOS only sees one core of one processor, having a cpu that is being ignored generating heat and other potential problems doesn't make sense.. If MorphOS ever supports multiple cores, then you already have a spare core in the 11,3, all good.

The single process PCIe PM creates the fastest possible MorphOS experience, as the hardware is just faster than any other PPC options out there like the X5000, peg 2, or SAM, and with them also being extremely reliable a win/win..


[ Edited by matt3 22.03.2026 - 05:01 ]

> 11,3

11,2 :-)