Closer Look: X99-A Motherboard
The ASUS X99-A follows the “LGA2011/2011-v3” motherboard layout we’ve seen before, with four DIMM sockets on either side of the CPU socket, and power supply circuitry at the top and side.
The included accessories comprise a manual, driver disk, a large case decal, four latching SATA cables, an I/O shield, ASUS’ “Q-connectors” for front panel audio and front panel ports, and finally a rather long dual-card SLI bridge. Considering that running a triple-card SLI or CrossfireX system is one of the main reasons to buy an X99 system, the lack of a 3-card SLI bridge is odd.
At the lower left edge of the board are pretty gold caps for the audio circuitry, the front panel audio header, a connector for an optional external fan controllers, a serial port header, (tiny)power and reset buttons, and a Trusted Platform Module header.
Moving past the TPM header, we see a USB 3.0 header, two USB 2.0 headers, and the front panel header. ASUS’ supplied “Q-connector” for the front panel header makes connecting your case’s front panel wires a snap.
There are six PCI-E slots, four x16 and two x1. With a 40-lane CPU such as our test Core i7-5960X, lane allocation with three cards is 16-16-8; with a 28-lane CPU, it’s 16-8-4. In either case the last PCI-E x16 slot is disabled if you’re using an m.2 SSD.
The rear I/O panel provides the USB Flashback button, a PS/2 combo connector for those of you still using antediluvian mice and keyboards, four USB 2.0 connectors, six USB 3.0 connectors, a gigabit Ethernet port, and a standard analog audio block with an optical out.
Let’s continue looking at this board in the next section.