Any z77 motherboard is going to fit all of those requirements with just two outliers - the memory (many will have a maximum of 32GB) and the ps2 mouse port/serial port. I can absolutely guarantee you that any modern motherboard will be without a ps/2 port, the serial port I'm less sure about. I would suggest looking for an add-on card you can use as it will make searching simpler. Sorry I can't make a recommendation on a board as I've never had to use that much memory, but given that is your only special requirement, it should make narrowing the choice down much easier. If you have a preferred retailer you could try looking through the z77motherboards in their pricing list for one that handles 64GB+ (or if its one of those older-style stores that actually offers decent service, phone them and ask - nostalgic!).