Try to clean all PCIE connectors. Fence likes to cause such errors.

Another tip:
You must recognise card that have problem.
You have 2 ways.
1. Disconnect all cards and then connect one by one and test.

2. Disconnect one card and test. If there is still error, disconnect another one. Last disconnected card was haveing problem (if only one have problem).

Regards

PS for cleaning i am using grain alcohol.