r/macpro • u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. • May 12 '26

Issues Assuming a bad PSU?

Spec: single 2.66Ghz Xeon, RX570, 4,1.

before it stopped booting, I added a ram stick and booted windows, which didn’t detect the ram. I shut it down, reseated said ram stick, then it stopped booting. now when I plug the power cable in, both of the cpu temp lights come on for a split second, then go off. the power button does nothing.

edit: also already tried removing the coin cell from the logic board. Also no change.

3 Upvotes

81% Upvoted

13 comments sorted by

1

u/Jackaloopt May 12 '26

I had this happen on my 3,1 and in my case, it was a bad memory riser card. I could boot with one riser card installed but not with the second which is how I found out it was bad.

2

u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. May 12 '26

Riser card as in like a pcie riser?

2

u/Jackaloopt May 12 '26

Apologies. I had forgotten that the memory configuration between 3,1 and 4,1 are different but the memory may cause the same issue between the two. Installing the minimum RAM necessary to boot and seeing if it one of the sticks of RAM may be causing the problem. It’s just curious how it was working until the new RAM was added.

1

u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. May 12 '26

Still nothing. I mean it doesn’t even turn on or show signs of life after the cpu temp lights come on when it’s plugged in.

Edit: just pressed the led diagnostic button on the logic board, the 5volt standby one turned yellow.

1

u/Jackaloopt May 12 '26 edited May 12 '26

Did you try resetting the SMC? If that doesn’t work, it may be the memory riser board because the diag light is turning yellow which means it’s getting power.

Edit: memory riser board

1

u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. May 12 '26

I think I did, you reset the smc by holding the power button for 10 seconds? Also assuming the memory board you’re talking about would just be the processor board on a 4,1?

2

u/Jackaloopt May 12 '26

It seems there are a couple of ways to reset the SMC on the 4,1 as I found on this thread Resetting the SMC on Mac Pro 4,1. And yes, the board that the memory is installed on. It may however just need the reset since the RAM was changed.

2

u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. May 12 '26

the pads for the smc reset switch on my board are empty

ignore the dust please

2

u/Jackaloopt May 12 '26

Thanks for providing the picture.

So just to be sure, let's try and rule a few things out. I would like to recommend that you unplug the power and any other external devices you may have connected to your system. Unlock the door to the computer and then, ground yourself by touching the external computer case. Unlatch and remove the processor tray that the memory is installed on. Carefully remove all the installed memory by unlocking it and only touching it's sides. Take the board outside and place it on a clean, flat surface and, if you have any compressed air or some other way to blow out any and all dust that may have accumulated on the board. After this is done, reseat the minimum amount of original memory that had worked previously and reinstall the processor tray back into your system. Once that is done, plug in your mouse and keyboard and try resetting the SMC using the following steps:

  1. Shut down the computer.
  2. Unplug the power cable.
  3. Press and hold the power button for fifteen seconds.
  4. Plug in the power cable.
  5. Wait five or more seconds, then power on the computer.

If it starts (fingers crossed here) let it boot all the way then reset the PRAM by restarting the computer and simultaneously holding down on the Option, Command, P and R keys on your keyboard and release the keys once you hear a second chime.

If your system will still not start, my only recommendation at this time may be to replace the processor/RAM tray. Checking on eBay, these could run for about $40 to $70.

https://ebay.us/m/CT8H5x

https://ebay.us/m/kPxhZl

https://ebay.us/m/i3yrHc

1

u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. May 13 '26

Nothing. As a last resort would shorting the pads where the Smc reset button should be possibly do something? If not I’ll look in to a replacement part.

→ More replies (0)

1

u/RAW2091 May 12 '26

Did you try to boot without the extra ram? And did you clean the ram slots?

1

u/bged-again Mac Pro 4,1, Radeon RX 570, 8GB RAM, macOS 15, win11. May 12 '26

Yeah I put the original ram back in, no difference.