I own a Dell XPS 435 MT and it still runs very well. It has 6 RAM slots and I have 3 x 4GB sticks running in slots 1, 2, and 3 (the three white slots, 4, 5, and 6 are the black slots). BIOS only sees 4GB now. All three sticks are the same size and speed and brand. They were purchased together a...