In terms of layout, things are a bit crowded compared to the Intel P55 boards we've reviewed so many of recently, due to a separate North and Southbridge and extra features, but nonetheless everything is mostly logical and tidy. The M4A89GTD's dual-channel memory slots are colour-coded with blue denoting primary, and can handle DDR3 up to 2,000MHz (overclocked).
Asus' unique QDIMM implementation means the slots only latch memory on one side to make installation and removal of sticks easier than ever. Beside these slots is a memOK! button - another feature unique to Asus boards - which will automatically tune any memory for optimum compatibility and has its own small LED to notify you if incompatibilities or errors are found.
Above the memOK! button are two physical switches for Turbo Key II and CPU core unlocking, courtesy of a hardware TurboV EVO chip. Much like MSI's OCGenie (as seen on the P55-GD65), Turbo Key II auto-tunes your CPU and RAM to get the best stable overclock from them. Hopefully it will leave us more impressed than MSI's equivalent did, but considering Asus already offers comprehensive overclocking options both from the BIOS and Windows, it's hardly an essential feature.
Far more interesting is the CPU core unlocking, which potentially lets you turn a tri-core Phenom II to a quad-core at the flick of a switch or push of a button. This is possible because tri-core chips are made from exactly the same design as quad-core products but one of the cores is disabled or 'binned'. Sometimes these disabled cores still actually work just fine after re-activation, though it's a complete lottery so certainly shouldn't be your primary reason for investing in this board..
That's about it in terms of enthusiast switches or buttons. You won't, for example, find physical reset, power or clear-CMOS buttons, but then these are only handy rather than essential.
At the bottom of the board we have no less than six SATA 6Gb/s ports, which is significantly more than the two provided on the Asus P7P55D-E Premium. This is because the P7P55D-E needed a separate Marvel controller paired with its Intel chipset to provide for the new SATA standard, while with the M4A89GTD Pro/USB3 it's natively handled by AMD's SB850 controller. Two SATA ports are angled and four are facing up, and they're all placed well out of the way of even the lengthiest graphics card coolers.
Though there is an angled EIDE connector, thankfully there's no sign of the entirely defunct floppy connector. Four USB headers provide eight potential extra USB ports and there's a FireWire header too, but Asus doesn't provide any expansion brackets for these. Mind you, there's plenty of connectivity on the rear IO, but we'll get to that in a bit.
Next to the aforementioned huge heatsink is a very unusual eight-pin 12V power connector, in that it stands as tall as the cooler. This is obviously to make sure that cables will reach it, and as a PC builder who's personally experienced the concomitant power cable falling just a few millimetres short it's a touch I certainly appreciate - though with most modern power supplies it shouldn't be an issue. Two three-pin and two four-pin fan headers (of which three support Asus' FanXpert, regulating rpm through the BIOS or software) are spread out over the board in convenient locations.