XServe G5 Cannot Boot Up via mac-boot -Alloc-MEM request too big!

[i200yrs]

Hello Experts...really need some helps here...I got these 2 units xserve g5 having same symptom showing open firmware when we tried to boot up.
The open firmware asking to do mac-boot to boot up...but when we tried the error came out -->ALLOC-MEM REQUEST TOO BIG!

We have total 3 units, but only 1 can boot up properly win mac OS windows.
The good unit which we swapped parts to problematic units to isolate and identify which part is possible reasons.
Swapped HDD -same result
Swapped RAMS -same result
Swapped PSU -same result.
Swapped CMOS batt -same result.

Am running out of option, I am suspecting the problematic units were configure to boot up NOT to hdd. But am not really sure.
Please check attached files for the failure screenshot.

 

[BradtheRad]

Things to try:

* Try the many keypress options available for Macintosh.

* Press Command-V at startup ('Verbose' mode). Each step of startup appears onscreen.

* Command-S (single user mode). Less verbose screen messages. Possibly has to do with networking.

* Option key. Lists attached boot disks for you to choose at startup.

* Command-PR. Resets PRAM.

* Locate the CUDA button inside enclosure. Pressing it performs certain reset functions. It might apply to your problem. It may be hidden behind components.

* Is G5 compatible with your OS?

* Try Target mode. You'll need a Firewire cable. Target mode connects a second Mac's hd to the first. Maybe there's a way to test as a boot disk.

* One way or another you should open Disk Utility and run First Aid on all your disks. Examine partition arrangements and sizes.
My OSX Mac has a utility partition running on a downsized OS which including Disk Utility. It pops up when normal startup is unsuccessful. It gives the option to reinstall OSX, etc. There ought to be a way to switch to it deliberately to do diagnostics.

* Your post says: "mac OS windows". Do you have more than one boot partition? It's not clear which OS you're talking about.

 

[i200yrs]

Hello BradtheRad...thanks for the reply...would like to answer some of your questions:
* Is G5 compatible with your OS? = Yes confirmed it is compatible, because we have 3 unit can perfectly boot using same hdd.
*Your post says: "mac OS windows". Do you have more than one boot partition? = It's mac OS...no partition

Let me try do some of your tips...and see what else i could try...thanks

--- Updated Nov 22, 2021 ---

Hello BradtheRad...have tried all the keypress options you provided but nothing changes, it still boot into open-firmware as shown on the attached file. Really running out of options...

 

[BradtheRad]

A message board recommends the 'Open firmware' message can be solved by reseating the Airport card.

Another place suggests the memory allocation error might go away if you remove one RAM card at a time. I guess because total RAM is too big for the OS to access it entirely.
Or, because of incompatibility with a certain brand of RAM, or unusable combination of capacities.

I believe there's a keypress option or utility that checks RAM on startup, or else allows you to bypass it in order to have quick startup.

Try removing all RAM, just to see if a different message pops up.

Your G5 probably is old enough that each card would benefit from getting the copper contacts cleaned.

 

[i200yrs]

A message board recommends the 'Open firmware' message can be solved by reseating the Airport card.

Another place suggests the memory allocation error might go away if you remove one RAM card at a time. I guess because total RAM is too big for the OS to access it entirely.
Or, because of incompatibility with a certain brand of RAM, or unusable combination of capacities.

I believe there's a keypress option or utility that checks RAM on startup, or else allows you to bypass it in order to have quick startup.

Try removing all RAM, just to see if a different message pops up.

Your G5 probably is old enough that each card would benefit from getting the copper contacts cleaned.

Yes i have tried removing just now the ram one by one and boot up...all got no changes except without ram totally black screen.
On the other hand, this unit does not have airport card.

Is there am open-firmware command to see boot sequence? thanks

 

[BradtheRad]

Macs search automatically for a boot disk. Try removing all internal hd's, so that it looks for any available disk. It's worth a try even though yours is the XSERVE G5... regardless if it usually starts from a server OS, or boots via a network, etc.

I successfully started my G5 from an external USB hd. It needs to be bootable. Startup takes a longer time than normal. I found a free cloning program to transfer the OS on it. I selected the option to 'create bootable disk'.

Firewire HD is faster than USB.

HD capacity needs to be compatible with your machine.

Look at these websites to see tech info about the XSERVE G5:

Lowendmac.com

**broken link removed**

 

[i200yrs]

hello BradtheRad...thanks for sharing the links...i find time explore later...I have tried removed all HDD but no changes...same result...i tried type mac-boot but also same result....do you think have problem in motherboard? thanks