To get the Inspur X540-t2 working (cut off or tape isolated pcie 1x connector at the end) on Mac Pro 2008 3,1 or other PCIE 2.0 motherboards read on! You do need to use slot 1 or 2 on Mac Pro because of 8x length requirement and full speed. In linux the card is running at 5GT 8x width in slot 1/2. The card is also detected and working with linux in slot 3 and 4 with 2,5GT and 4x width.
Solder / short PCI-E Bpin48 (PRSNT-2) with Bpin49 (ground). Just a tiny drop of tin and smear it out (Bpin47 is also ground) see green on photo. The B-side of PCI-E is the side with chipset & cooler, the PRSNT-1 Apin1 is already shorted so no jump wire needed. Look on wikipedia or other places for info about this PCI-E PRSNT (hot)plug presence detection in relation to slot width and length. This card was simply missing its length indicator.
View attachment 2344489
Only in Linux ubuntu 23.10 the card works with 2 ethernet adapters detected, but out of the box on Mac OS Montery 12.7.1 it is detected as 2 ethernet cards but the system will freeze as soon as a cable gets connected. Just checked the MacOS driver that is loaded with the OCLP monterey install is "com.apple.DriverKit-AppleEthernetIXGBE".
Reading previous comments in this topic it looks like more people have this issue when not using the smalltree driver where connecting of a ethernet cable leads to kernel panic on certain cards/chipsets.
Please let me know if different kext or eeprom id works now, because I'm totally not into MacOS kextloading or patching anymore.
Just figured this soldering trick tonight ;-)