TL;DR: My MacPro4,1 was having random cryptography issues, then the CPU tray reported the CPU as missing and refused to boot. After removing the Northbridge heat sink, the machine reports the CPU as alive and well.
To give a bit of context, I had bought a MacPro4,1 off Kijiji locally to help out with development of OpenCore Legacy Patcher. The machine was honestly horrid to look inside with the amount of dust, so when I got her home I cleaned her out. When I looked at the CPU tray, I noticed a plastic peg had been broken. At the time I didn't think much of it and so dusted the rest of the machine off and installed macOS Monterey on an NVMe drive.
Later on, I found that this plastic peg was actually one-half of the Northbridge's heat sink.
A couple of days pass and I start getting weird NVMe issues. I believed them to be quirks of the dated 4,1 firmware so decided to firmware flash my machine to a 5,1 in anticipation of a Xeon X5670 I got off eBay (but wouldn't arrive till September). The issues persisted with the firmware flash.
I assumed that the CPU itself was dead due to the weird crypto errors, so was going to wait till the new CPU arrived. I then did a lot more cleaning, looking at the socket for issues but to no avail. However, after a bit of discussion with a user on my Discord server, ylluminate, they mentioned an issue with the CPU Tray/Northbridge on one of their 4,1 (flashed 5,1) systems. They opted to replace the whole tray at the time due to time reasons but this gave me an idea, what if the Northbridge has too much one-sided pressure on it from the broken heatsink?
I followed this up by first removing the chipset heatsink and booting as is. And wouldn't you know, the thing booted! I later threw some zip ties on the heatsink and an abundance of thermal paste to aid with the thermal transfer, as I was afraid any pressure would cause the issues to pop up again.
I may in the future invest in a dual-socket CPU tray however seeing the overpriced market on eBay, I might wait till someone wants to donate one for OpenCore Legacy Patcher development ;p
I would be quite curious whether others have experienced something similar with their northbridge, would love to hear other reports.
Machine Specs
Code:
MODEL: MacPro4,1 - Early-2009 (Flashed to MacPro5,1 - 2010)
CPU: Xeon W3520 @ 2.66GHz
RAM: 16GB DDR3 1066Mhz (4x4GB)
GPU: AMD RX470 (RX5700XT tested)
SSD: WD SN750 1TB NVMe
WIFI: BRCM94360CD
OS 1: macOS Monterey (12.0 Beta 4)
OS 2: macOS Big Sur (11.5.1)
OS 3: Windows 10
To give a bit of context, I had bought a MacPro4,1 off Kijiji locally to help out with development of OpenCore Legacy Patcher. The machine was honestly horrid to look inside with the amount of dust, so when I got her home I cleaned her out. When I looked at the CPU tray, I noticed a plastic peg had been broken. At the time I didn't think much of it and so dusted the rest of the machine off and installed macOS Monterey on an NVMe drive.
Later on, I found that this plastic peg was actually one-half of the Northbridge's heat sink.
A couple of days pass and I start getting weird NVMe issues. I believed them to be quirks of the dated 4,1 firmware so decided to firmware flash my machine to a 5,1 in anticipation of a Xeon X5670 I got off eBay (but wouldn't arrive till September). The issues persisted with the firmware flash.
Main issues
The main concerns I noticed (in order):- Firmware failing to see NVMe drive in UEFI
- NVMeDxe already loaded via OpenCore, flashing to 5,1 seemed to fix the issue
- Trying to let Fortnite (in Windows 10) auto-configure settings would crash the hardware
- At first, seemed to be the PSU overloaded, however, the issue persisted on other cards
- Booting macOS would fail on cryptography verification relating to the APFS seal
- This would report on every SSD I installed, including those that boot fine in other machines
- macOS USBs would start to error on mismatched BaseSystems
Cryptography errors | CPU Tray light |
|
I assumed that the CPU itself was dead due to the weird crypto errors, so was going to wait till the new CPU arrived. I then did a lot more cleaning, looking at the socket for issues but to no avail. However, after a bit of discussion with a user on my Discord server, ylluminate, they mentioned an issue with the CPU Tray/Northbridge on one of their 4,1 (flashed 5,1) systems. They opted to replace the whole tray at the time due to time reasons but this gave me an idea, what if the Northbridge has too much one-sided pressure on it from the broken heatsink?
CPU Socket intack | NorthBridge |
I followed this up by first removing the chipset heatsink and booting as is. And wouldn't you know, the thing booted! I later threw some zip ties on the heatsink and an abundance of thermal paste to aid with the thermal transfer, as I was afraid any pressure would cause the issues to pop up again.
OpenCore Boot Picker Loaded | macOS loaded |
Concluding thoughts
From this odd situation, it seems the Northbridge became quite sensitive to pressure after the last user had the heatsink broken on one side creating an unbalanced distribution. Zip ties and thermal paste did fix it though how long this northbridge will last is up for debate.I may in the future invest in a dual-socket CPU tray however seeing the overpriced market on eBay, I might wait till someone wants to donate one for OpenCore Legacy Patcher development ;p
I would be quite curious whether others have experienced something similar with their northbridge, would love to hear other reports.