MP 1,1-5,1 Mac Pro 4,1 reboot loop after startup boot chime

[SolidCake]

Hi all,

My Mac Pro 4,1 (flashed to 5,1) enters a reboot loop when I start up the Mac. It keeps looping indefinitely until I manually turn it off by holding down the power button. When I turn it on again, or for the first time, it sometimes makes it past the boot screen and shuts down at the black loading screen with the Apple logo (loading bar at about one-third). It then automatically reboots and enters a loop where it keeps rebooting right after the startup chime; sometimes, it reboots before the end of the chime.

I tried resetting the PRAM, but that doesn't work, I'm holding down the buttons, but nothing happens.

Mac Mac:

• 4,1 flashed to 5,1
• OS: macOS Big Sur 11.4 (Open Core)
• Dual Xeon X5690's
• Dual AMD RX480 8GB (single six-pin version)
• Sonnet Allegro USB-C 4 port PCIe
• 2 x Samsung 850 EVO 500GB SSD
• 1 x Samsung 860 QVO 2TB SSD

Any help is welcome!

 

[tsialex]

Physically remove all your disks from your Mac Pro, yes, all. Insert a Mojave createinstallmedia USB installer.

See if you can boot it.

 

[cdf]

OS: macOS Big Sur 11.4 (Open Core)

See

Mac OS 11.3 has broken support for older Mac Pros

macOS Big Sur 11.3 Beta 3 has broken Mac Pro's early-2009 to mid-2012 ability to boot reliably into macOS. It's still possible to boot 11.3/11.4, but the process requires multiple restarts and a connection has been made between PCIe devices, especially storage related devices and USB controller...

forums.macrumors.com

 

[SolidCake]

Thanks for the replies!


Here's what I did:

• Rolled back the OS to 11.2.3
• Applied Open Core 0.6.9
• Issue still persists
• Removed all the PCIe
• Unplugged all ports
• Installed stock GPU (Apple GeForce GT120)
• Issue still persists

Right now, I'm hoping it is not a hardware issue related to the CPU tray/logic board.

If anyone has some more suggestions I'd be happy to hear them!

 

[tsialex]

Thanks for the replies!


Here's what I did:

• Rolled back the OS to 11.2.3
• Applied Open Core 0.6.9
• Issue still persists
• Removed all the PCIe
• Unplugged all ports
• Installed stock GPU (Apple GeForce GT120)
• Issue still persists

Right now, I'm hoping it is not a hardware issue related to the CPU tray/logic board.

If anyone has some more suggestions I'd be happy to hear them!

Flash your clean/backup BootROM dump.

 

[SolidCake]

Flash your clean/backup BootROM dump.

How do I go about doing that?

 

[tsialex]

How do I go about doing that?

To flash a BootROM image you will use ROMTool from a supported macOS, never flash booted from OpenCore, install and SIP needs to be disabled.​

​

First enter Firmware Programming Mode correctly.​

​

1. Shutdown your Mac,
2. Press and keep pressed the power button,
3. You will hear a loud beep, keep pressed,
4. You will hear the startup chime (if your Mac still has it, some Macs lost the chime with MP51.0087.B00), release the power button when it ends or when starts loading macOS (if your Mac lost the chime).
5. After you login, you can proceed to the flashing process with ROMTool

Open ROMTool:​

1. Click "Flash System ROM",
2. Open your back-up/clean BootROM dump.
3. Flash it,
4. Shutdown your Mac Pro.
5. Remove the power cable for at least 20 seconds to reset the SMC controller.
6. Connect the power cable and power on your Mac Pro.

 

[SolidCake]

To flash a BootROM image you will use ROMTool from a supported macOS, never flash booted from OpenCore, install and SIP needs to be disabled.​

​

First enter Firmware Programming Mode correctly.​

​

1. Shutdown your Mac,
2. Press and keep pressed the power button,
3. You will hear a loud beep, keep pressed,
4. You will hear the startup chime (if your Mac still has it, some Macs lost the chime with MP51.0087.B00), release the power button when it ends or when starts loading macOS (if your Mac lost the chime).
5. After you login, you can proceed to the flashing process with ROMTool

Open ROMTool:​

1. Click "Flash System ROM",
2. Open your back-up/clean BootROM dump.
3. Flash it,
4. Shutdown your Mac Pro.
5. Remove the power cable for at least 20 seconds to reset the SMC controller.
6. Connect the power cable and power on your Mac Pro.

Thanks for the detailed explanation! Just tried it, sadly did not work (the beep went off but still rebooted after I logged in). I noticed that I leave my Mac off for a while and turn it back on I can make it to logging in before it shuts down automatically. If I immediately turn it off and on again, it reboots at the Apple logo loading screen. Could it be that the battery might need to be replaced?

 

[tsialex]

Thanks for the detailed explanation! Just tried it, sadly did not work (the beep went off but still rebooted after I logged in). I noticed that I leave my Mac off for a while and turn it back on I can make it to logging in before it shuts down automatically. If I immediately turn it off and on again, it reboots at the Apple logo loading screen. Could it be that the battery might need to be replaced?

Always check the voltage of the BR2032C battery and replace it whenever is lower than 3V. A BR2032C battery will die fast after it's below 3.0V and the RTC will be stuck with 2.8V.

You probably have PSU (at least 11 years old by now, probably 12) or backplane problems, RX 480 single 6-pin are know to damage Mac Pro backplanes overtime with the excessive power draw from the PCIe slot.

 

[SolidCake]

Thanks for the quick reply! I'll go and check the battery; I hope it's just that as I have never replaced it...

I'll update the thread/post if something major happens.

 

[KeesMacPro]

1 x Samsung 860 QVO 2TB SSD

The Samsung QVO series is known for issues in the MP 4,1/5,1 .
I dont know if this is the culprit , but it's recommended to replace this drive for e.g. a 860 EVO

 

[Macschrauber]

Had such a drive for a customer built and we ended using it as a data drive. Crashes on system boot and disappeared after warm boot.

 

[SolidCake]

Hi all,

Thank you for all the replies and helpful information! I would like to give a short update on the current situation:

Before this issue came to light I had no issues running my Mac Pro on the latest OS with Open Core. I was exempt of problems regarding the issues mentioned in the Mac OS 11.3 has broken support for older Mac Pros thread.

This issue came out of the blue.

As of this post the LED's on the motherboard (vertical one, I don't know how it's officially named) give a green PSU light and amber 5v light. On the processor tray none of the warning lights are showing and I'm getting the bright red light flash for a moment when booting. So all seems good and healthy...

I did notice one other thing. Normally, when I would boot up the Mac, the fans would go crazy for a while, spinning really fast and making lots of noise. This would subside after a while. Now, the fans spin normally barely making any sound. Would this imply anything?

At the moment, I am at a loss as to what may be causing this issue. When taking out all the drives, and reverting to minimum ram and stock GPU; I am still getting the same issue.

The next thing I am going to try is taking out the CPU's, reapply thermal paste and put them back in, maybe they aren't seated correctly.

If anyone has some more suggestions, please let me know!

 

[tsialex]

Hi all,

Thank you for all the replies and helpful information! I would like to give a short update on the current situation:

Before this issue came to light I had no issues running my Mac Pro on the latest OS with Open Core. I was exempt of problems regarding the issues mentioned in the Mac OS 11.3 has broken support for older Mac Pros thread.

This issue came out of the blue.

As of this post the LED's on the motherboard (vertical one, I don't know how it's officially named) give a green PSU light and amber 5v light. On the processor tray none of the warning lights are showing and I'm getting the bright red light flash for a moment when booting. So all seems good and healthy...

I did notice one other thing. Normally, when I would boot up the Mac, the fans would go crazy for a while, spinning really fast and making lots of noise. This would subside after a while. Now, the fans spin normally barely making any sound. Would this imply anything?

At the moment, I am at a loss as to what may be causing this issue. When taking out all the drives, and reverting to minimum ram and stock GPU; I am still getting the same issue.

The next thing I am going to try is taking out the CPU's, reapply thermal paste and put them back in, maybe they aren't seated correctly.

If anyone has some more suggestions, please let me know!

If EFI_DONE LED is off when you press the DIAG button, you have a brick.

Use the search for EFI_DONE, no need to re-write it here again.

 

[SolidCake]

Hi all,

Recently I found the time to install a used backplane described as working (bought it from eBay). I installed it and still no luck. The issue I'm encountering are still the same: RAM chime -> boot -> login -> and restart. The restart loop then continues until it hangs on a grey screen.

I found another thread where someone has somewhat the same issue I have.

I noticed the backplane I got from eBay has the same 'flux/cap leak' marks on the back. Did I get a defective backplane?

Here's a picture of it:

Could it still be the backplane that is causing this issue? As of right now, I have no idea what could be the problem. If anyone has some suggestions, please share!

All the best and a happy new year!

Cheers!

 

[tsialex]

Did you tested with a know working PSU?

 

[SolidCake]

Hi all, my Mac Pro 4,1 is working again!

@tsialex suggested I replace the PSU, and I got a refurbished one from eBay, and it's working now!

I think it was a combination of a faulty backplane and PSU.

Before I replaced the backplane, I could not reset the PRAM anymore. When I replaced the backplane, I could get the PRAM to reset, but it would still shut down after logging in. When I then replaced the PSU, everything started working again!

Thanks for all the help!

Cheers!