The 965 uses socket AM3 and has 938 pins. It is therefore not pin compatible with Socket F, which is used for dual processor AMD severs and uses 1207 pins.
With the older Xeons based on the Core microarchitecture, socket 775 is used for single processor systems, LGA 771 for dual processor systems, and LGA 604 for quad. You need the right type of CPU to fit the socket.
With the new Nehalem Xeons, LGA 1336 is used for both single and dual processor systems, but you will need a CPU with only one QPI link to run in a single CPU motherboard and one with two QPI links to run in a DP motherboard. Core i7-9xx and Xeon 35xx work in single socket systems. Only the Xeon 55xx will work with dual sockect systems.
Intel also released LGA 1156 to replace LGA 1336 in the single processor server market. With LGA 1156, any CPU using that socket will work, including the Xeon 34xx series, Core i5-750, and i7-8xx.