Asus puts all four of the P9X79’s USB 3.0 ports on the rear panel, eliminating the possibility of a front-panel header. The board does, however, retain eSATA and IEEE-1394 ports from its more-expensive siblings, along with Asus’ USB BIOS Flashback and Quick BIOS Screen Capture features.
USB BIOS Flashback uses a custom IC to enable firmware flashing from a USB drive with no other hardware installed. That’s particularly beneficial to users who actually need a firmware update to simply support hardware they bought with the board. As you'll see shortly, this is a very real concern, and a competitor was affected by its inability to accommodate our C2-stepping processor right out of the box.
The P9X79 beats several competing products in maximum memory support by including eight slots. While the board also gives up any additional SATA ports, most enthusiasts will expand beyond four modules long before they see the need to expand beyond the X79 Express' six SATA ports.
The P9X79 includes switches and a button for Asus’ EPU, TPU, and MemOK modes. EPU is an automatic underclocking routine for enhanced power savings under low loads, TPU is an automatic overclocking routine, and MemOK temporarily underclocks memory to ease booting with improperly-programmed modules.
Like most other entry-level X79-based platforms, the P9X79 relies on Sandy Bridge-E’s 40 PCIe 3.0 lanes to support up to three graphics cards with x16-x16-x8 connections. Asus pushes the x8 slot to the bottom of the board, however, where installing a dual-slot graphics card requires an eight-slot case (in addition to smashing flat any cables connected to headers along the board’s bottom edge). This is particularly frustrating for users who hoped to take advantage of Asus’ Q-Connector cable bundling feature. Dual-card users fare better, since the board provides an extra space between its two x16 slots for improved airflow.
Though the P9X79 supports three graphics cards, it does not include a three-way SLI bridge. A two-way SLI bridge, I/O shield, and four SATA cables complete its installation kit.