I brought in another Z800 system that has no additional cards aside from an lower level mid range nvidia and can update a little more details.
The cards work normal/as expected with only one 10gig connection in place. When I connect a second 10gig cable, the card over heats in about 20-30 seconds.
These are being installed into the last (bottom) port, however port swapping doesn't fix this. Cards are certainly seated.
Now, if I position an 80mm fan perpendicular to the card so it blows air directly onto the heat sync, this will prevent the card from overheating with two 10gig connections
The X540-T2 card has an "over temp" LED at the back. Do you know if it is in any way possible to retrieve the card or chip's temperature programmatically, i.e. through SNMP, IPMI or any such means?
X540 FAQ 2.35 implies it's up to the board manufacturer to design a temperature sensor into the board. I.e. Intel, in this case
I am also interested in such facilities for X540-T1 and 82599EB, which have no such LEDs.