I have the AX8. Highly recommended with PCI-E and four SATA ports, two firewire 1394, and eight USB 2.0. There are four fan headers on the motherboard (two controlled by onboard software). Have no problem overclocking my Winchester 3000 to 3700 speed. I use value RAM so LDT is set to 4x and RAM to DDR333 (263 MHz FSB x 9 multiplier). Also bumped CPU VCore to 1.525 V.
If the case does not vent well, then use 250 MHz FSB with 1.425 Vcore. The $100 AX8 is only 1.5% slower than the much more expensive Fatal1ty AN8.
Be sure to connect the molex power connector from the power supply to the one at the bottom of the motherboard. This will supply extra juice to the PCI-E video card. You don't need a power supply with a special PCI-E plug with the AX8 board.
I would definitely go with a quality power supply if you are going to purchase a powerful video card. Fortron, Enermax, and Seasonic are good brands. 450 to 500W would be ideal for future expansion. A 350W unit will also run well if you don't overload the system.