Hi, Both the 7450 and 7460 are validated CPUs. You should not need to replace the system board for the newer CPUs, just BIOS 1.1.9 or newer. 
I have an R900 with a C764H motherboard and four XEON E7330 CPU's. These CPU's are not supported by VMWare ESXi 6.5  however the XEON E74xx series is. 1) the 7330 is a quad-core, 2.4GHz, 2x3MB L2 Cache.  the 7440 is also a quad-core, 2.4Ghz, 2.3MB L2 cache.  i assume i could simply drop in 7440's without any problem.  is this correct? 2) the E7450 is a 6-core, 2.4GHz, 3x3MB L3 cache CPU.  can i drop these in, or do i also need to change the motherboard to one that works with 6-core CPU's? 3) if the answer to #2 is a yes (that i do not need to change motherboards), could i use X7460 which is the same as the E7450, but with a faster clock (2.66GHz instead of 2.4GHz)?  or do i need a different motherboard that supports the faster clock speed? THanks
PowerEdge R900 motherboard upgrading CPU's