The ASUS M5A99X EVO motherboard has the following technical specifications as advertised:
CPU - AMD AM3+ FX™/Phenom™ II/Athlon™ II/Sempron™ 100 Series Processors including AM3+ 32 nm CPU, up to 8 cores, up to 140 W
Memory - 4 x DIMM, Max. 32GB, DDR3 1866/1600/1333/1066 Hz ECC, Non-ECC, Un-buffered Dual Channel Memory Architecture
Multi-GPU - Supports NVIDIA® Quad-GPU SLI™ Technology and AMD Quad-GPU CrossFireX™ Technology*
Expansion - 2 x PCIe 2.0 x16 (dual x8)
1 x PCIe 2.0 x16 (x4 mode, black)
2 x PCIe 2.0 x1
1 x PCI
Storage - AMD SB950 controller : 6 x SATA 6Gb/s port(s) white support Raid 0, 1, 5, 10
JMicron® JMB362 controller : 2 x SATA 3Gb/s port(s) black, 1 x Power eSATA 3Gb/s port(s) green, 1 x eSATA 3Gb/s port(s) red
Network - Realtek® 8111E , 1 x Gigabit LAN Controller(s)
Audio - Realtek® ALC 892 8-Channel High Definition Audio CODEC
1394 - VIA® 6308P controller 2 x IEEE 1394a port(s)
USB - ASMedia® USB 3.0 controller : 4 x USB 3.0 port(s)
AMD SB950 controller : 14 x USB 2.0 port(s)
* You'll note that the only difference between these specifications and those of the Sabertooth 990FX is the number of PCI-E slots. The claim that the 990X supports Quad SLI or CrossFireX is a bit of a misnomer, obviously with only two PCI-E x16 slots (limited to x8 in dual mode) this board is incapable of supporting four graphics cards. However dual processor cards like the nVidia GTX 590 or ATI HD6990 do technically provide SLI/CrossFireX functionality through a single slot, however I wouldn't necessarily recommend running these on an x8 limited interface. If you've got the money to spend on two of these cards, you can probably afford a true dual x16 architecture motherboard.
Despite the new 990X/SB950 nomenclature, there's really nothing new here that the 890GX/SB850 didn't already offer. USB 3.0 is still not supported natively, and with only six SATA ports available manufacturers are still relying on extra controllers to offer additional ports or eSATA capability. Although the DDR3-1866 memory speed is now officially supported on AM3+ processors, this is a function of the integrated controller, and some overclockers have already gotten up to 1000MHz or more out of the existing AM3 chips. My personal best so far has been 912MHz or DDR3-1824 with an OCZ Platinum XTE kit.
Let's get the board unwrapped and take a look at some of the features.