I have a Precision 3450 SFF, Xeon w1350, 48Gb (3x16Gb) on latest BIOS (1.28) with Proxmox pve 8.1.  This was running fine for months.  It has one 512Gb and one 2Tb NVME. 

Next to the onboard NIC, it also has a IBM Dual port NIC i340-T2 in the PCI-e slot.  As I had trouble in finding a quad port card I wanted to add, I took a one port intel desktop NIC.  So, I shutdown the machine, opend the case and added the NIC into the video slot.  Closed the case and start. 

The moment Proxmox shows the number of volumes, the machine shutsdown from the power.  It is not possible to use the on/of switch to get power back. 

First thing I tried was a HW-reset – powercord off, battery out and 20-secs on.off.  When I reverse that I have to bring back some bios items.  Restart the machine: same failure.

Took out everything (RAM, NVME's, NICS, all) but for one memory (16Gb) in DIMM1 and started Debian live…  Same thing.  So my guess is it is mobo related?  BIOS realted?

So, it could be this one port NIC was faulty (new to me but 2nd hand), or adding it into the video pci slot did something terrible to the machine…  Can that be the case?

I forgot one of those rules: when working on a machine, first restart before you do anything to it.  So I am not sure if it is the one port NIC or this issue was already there but not harming as long as the machine was running.

Whatever, I am at lands-end.  Anybody with an experience like this?  Is there a solution (into the basketbin is one of those but that will hurt…) or some suggestions to do some more troubleshooting.

Thx