SuperMicro X7DBE dual Xeon dont see 2. CPU -HELP-

[Milos]

I have two Super Micro X7DBE S771 dual Xeon MB with two E5430 Xeons on each board .On each board is 8x2GB of RAM all slots full. The problem is that MB don't see second CPU.
When it starts there is message 1 of 1 CPU enabled , but few days it was 2 of 2 CPU enabled.
When I switch CPU in socket it is the same , so CPUs are ok .
If I leave one CPU in socket 2 , MB don't show anything on screen but cooler starts.
I have tried with different RAM configurations and it is the same.
I tried with two different PSUs it is the same.
Reset of BIOS and it is the same.
Looked in the manual for maybe some jumpers, but no jumpers for CPU configuration.
In Bios found no options to enable second CPU.
System is Win 10 Pro 64bit.
I think it is MB , but I would appreciate if anyone else has any idea what to try more.It would be nice if this could continue working for some time more.

 

[Terry Kennedy]

I think it is MB , but I would appreciate if anyone else has any idea what to try more.It would be nice if this could continue working for some time more.

The "usual suspects" are bent pins in the CPU socket, bad connection on the 2nd EPS12V power cable, or rogue expansion cards / memory. Those tend to happen on new builds, not on working systems, though. I'd suggest temporarily removing all expansion cards and all but the bare minimum of memory, check the 2nd EPS12V connection (you say you swapped power supplies, but if they were modular you're still using the original PDB and cabling) and look at the 2nd CPU socket with a low-power magnifier to look for lint in the socket or bent pins. It could also be in the CPU 1 socket, if the pins in question are the inter-CPU link.