Let's just say that PCI Express ports confuse may. I know that they are generally used for expansion cards, but the difference between an Express 16x slot, Express 8x slot, Express 4x, and an Express 1x. The mini ITX has 3 Express 16x slots running at 16, 8, and 4, with one PCI Express 1x. The ATX board has the same 3 Express 16x, but has 3 PCI Epress 1x and one regular PCI. I don't think I will be using too many expansion cards. Maybe a wireless adapter card, capture card, and possibly a sound card. Any other differences between the boards that may concern me I would like to hear about. For instance the audio in the 2 seem different, but other than that they seem very similar.