So I have a Dell Dimension E520 from 2006, came with a Pentium D 2.80 and the socket is PLGA 775. Now, theres not very many options, but I was wondering if there was a 64 bit processor for PLGA 775 (not to be confused with LGA 775), and if it was replaced with that processor, would I be able to plug in over 4 gb of ram? Also, the current motherboard only supports DDR2 533, 667, and 800, and would it be worth upgrading the motherboard for DDR4?