No need to check the CPU socket, bent pins would not affect memory on this system.
Can you test each stick of memory one by one, in the first slot on the motherboard to be sure the sticks are all working. Then test a stick in each slot on the motherboard to be sure each slot is working as it should.
If all of that passes, did you upgrade from XP or from a 32 Bit system to x64, or was it a clean install? If it was an upgrade I've seen this issue in the past, and you will need to do a clean install of 64 to correct it.