1. You cannot mix and match processors. They must be the same. If you do not see one on our site, contact sales. Not all our parts are available online.
2. If you order the processor, make sure the heatsink is included. Memory must also match on both sides.
3. The server has 3 channels per side, 2 DIMM's per channel. Each channel needs to be identical. When upgrading memory, make sure you order the correct ones to match what is currently installed, either UDIMM or RDIMM. They cannot be mixed either. For more memory information, check out the technical guide located here: http://www.dell.com/downloads/global/products/pedge/en/server-poweredge-t610-tech-guidebook.pdf
Regards.