Getting onto PCI slots we have two 16x PCIe slots with plenty of breathing space between them, three 1x PCIe slots and two of the old PCI variety for those who want to install older cards. That's certainly plenty for most users, though a single dual-slot graphics card will cover one of the 1x PCIe slots while a second would cover one of the PCI slots. Just as with the clever memory retention mechanism, another nice touch here is that the latches for holding in the graphics card(s) have been modified to be easier to reach with a card installed.
It should be noted that despite offering both CrossFire and SLI compatibility, as with other P55-based motherboards the Sabertooth 55i only supports eight lanes per channel when using dual graphics cards, so if you want every last drop of performance out of your dual video cards you're still better off with an X58-based system.
Getting onto the Sabertooth's rear I/O connectivity, we have PS2 connectors for mouse and keyboard. While the latter arguably still makes sense for BIOS problems, there is simply no reason to still have PS2 mouse compatibility on a modern enthusiast motherboard. Eight USB2 ports should be plenty though, especially since a bracket is included with a further two ports, still leaving two USB headers (for four ports) free on the motherboard. There's one eSATA connection on the backplate (just above a FireWire port) and another on the bracket.
For audio we have a single optical digital output (a bit stingy considering most motherboards in this class offer both optical and co-axial) plus six analogue jacks that can output DTS or up to 9.1(!) surround sound from the board's VIA VT2020 10-channel audio chipset - definitely a step up from most. Finally a single Gigabit Ethernet port takes care of networking.
As one would expect from a manufacturer who's been in the game as long as Asus, the BIOS offers more options than you can shake a stick at yet is logically laid out (one slight exception being that the Hardware Monitor is found under Power).
The two most interesting menus aside from the usual suspects are A.i. Tweaker and Tools. As the name implies, A.i. Tweaker includes 'intelligent' overclocking options, though you're better off using manual settings for the best overclock. Under Tools you'll find up to eight fully-configurable overclocking profiles, which can be saved to or loaded from either the BIOS or external storage.