what could be checked
1) install actual drivers for NIC according UCS SW/HW version (http://www.cisco.com/web/techdoc/ucs/interoperability/matrix/matrix.html ). Increase amount of queues on UCS side from default to recommended and buffer size. (http:...
I faced with the same issue on RedHat 6.5 2.6.32-431.23.3.el6.x86_64 kernel.
proprietary driver 2.1.1.75 (from cisco.com) is installed according reccomendation from http://www.cisco.com/web/techdoc/ucs/interoperability/matrix/matrix.html for our U...