Table 3 Available CPUs: Intel Xeon Westmere E7-28xx/8867L Family
http://www.cisco.com/c/dam/en/us/products/collateral/servers-unified-computing/ucs-c-series-rack-servers/c260m2_specsheet.pdf
Comparison of all C-Series server can be found in
http://www.cisco.com/c/en/us/products/servers-unified-computing/ucs-c-series-rack-servers/models-comparison.html