T730 thin client - won't boot properly with 10G PCIe NICs

[Beer_Can]

Tried several makes and models of Intel x520-DA2 cards in T730, so we can effectively exclude fakes.

The machine will only boot occasionally with one of these cards installed in the PCIe slot.  Not reliable enough for service.  Disabling the PCIe card in "Slot Security" ensures booting, but obviously puts the NIC off line.  I have disabled all Option ROM selections in BIOS.  Disabling on the T730's inbuilt re NIC didn't help either.

Gbe NIC cards work without issue, I'm not sure what is glitching out on the 10G ones.

BIOS is 1.16 Rev A, the latest.

A bad boot has the power light on, but no drive activity LED, and the video never wakes the monitor.  The behaviour is the same whether Windows, Linux or other UNIX.  Some boots work ok.  I have blanked off pins B5 & B6 on the cards which helps, disabling SMBUS, but still some boots come up stalled.

I see reports of various 10G cards (inc Mellanox) causing similar behaviour since around BIOS 1.15 .  

Attempting to find earlier versions of the BIOS is fruitless, and 1.14 (SP93015) is apparently removed from ftp3.hp.com/pub so I cannot test.

A second SODIMM may also be interfering.  

This all sounds like a BIOS issue that I would be interested to see whether 1.14 or earlier would resolve.

Grateful to get this up and running.  Thanks.