We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.

[nextpage title=”Introduction”]

The ASUS X99-A is a mid-range motherboard for the new Intel high-end “Haswell-E” processors, based on the new LGA2011-v3 socket. It includes three PCI Express 3.0 x16 slots, ten SATA-600 ports (with one SATA Express connector), ten USB 3.0 ports, and a high-end audio controller. Let’s take a good look at this board.

The new Intel X99 platform supports the new socket LGA2011-v3 processors. However, it is not compatible with former socket LGA2011 CPUs, which require motherboards based on the Intel X79 chipset. The main difference between the two platforms is that LGA2011 processors are compatible with DDR3 memories, while LGA2011-v3 CPUs can use the new DDR4 standard.

The main differences between the X99 and the X79 chipsets, besides the CPU support as mentioned above, are the number of USB 3.0 and SATA-600 ports: the X99 offers ten SATA-600 and six USB 3.0 ports, while the X79 supports only two SATA-600 ports and has no native support for USB 3.0 ports.

In Figure 1, you see the ASUS X99-A motherboard. There are details in white on the heatsinks that give the motherboard a nice, clean look. It uses the ATX form factor (12 x 9.6 inches or 305 x 244 mm).

ASUS X99-AFigure 1: ASUS X99-A motherboard

[nextpage title=”Slots”]

Socket LGA2011-v3 processors have a maximum of 40 PCI Express 3.0 lanes (some models have only 28 lanes) for video cards. This allows a very high-end configuration for the PCI Express x16 slots when a CPU with 40 lanes is installed, but the exact configuration used will depend on the model of the CPU that will be installed.

The ASUS X99-A comes with three PCI Express 3.0 x16 slots. With a 40-lane processor installed, the board supports x16/x16/x8 configuration. With a 28-lane CPU, the board supports x16/x8/x4 configuration. In both cases, the last slot shares bandwidh with the M.2 slot. If the M.2 slot is used, the fourth PCI Express x16 slot is disabled.

There is also one PCI Express 2.0 x16 slot, which works at x4 maximum speed (x1 speed if the additional USB 3.0 ports are enabled), and two PCI Express 2.0 x1 slots.

The motherboard supports three-way SLI and CrossFireX setups, with up to four GPUs.

When installing dual-slot video cards, you “kill” the slot immediately to the left (looking at the motherboard with its rear connectors facing up) of the slot being used. Therefore, if you install a dual-slot video card in the first, second, or third PCI Express x16 slot, you will be unable to use the slot to its immediate left. You can only install a dual-slot video card at the fourth PCI Express x16 slot if you are using a case with eight expansion slots.

ASUS X99-AFigure 2: slots

THe X99-A comes with one M.2 slot, shown in Figure 3. However, this slot supports only PCI Express M.2 cards, and is not compatible with SATA M.2 modules. As explained, this slot shares bandwidth with the fourth PCI Express x16 slot.

ASUS X99-AFigure 3: M.2 slot

[nextpage title=”Memory Support”]

Intel socket LGA2011-v3 CPUs have an embedded memory controller, meaning that it is the processor, not the chipset, which defines what memory technologies you can have and the maximum amount of memory that is possible. The motherboard, however, may have a limitation as to how much memory can be installed.

The integrated memory controller from socket LGA2011-v3 processors officially supports DDR4 memories up to 2,133 MHz. According to ASUS, the X99-A supports memories up to 3,200 MHz.

One of the most important features of the socket LGA2011-v3 processors is the support for the quad-channel memory architecture, which allows the memory to be accessed in 256-bit mode for higher performance. Since each memory module is a 64-bit entity, four memory modules are needed to enable this architecture. If only two or three memory modules are installed, the memory will be accessed under dual- or triple-channel architecture, respectively.

The ASUS X99-A has eight memory sockets (four at each side of the CPU socket) and you can have up to 64 GiB with this motherboard if you use eight 8 GiB modules.

In order to enable the quad-channel mode, you must install four or eight identical memory modules. When installing four memory modules, you will have to “skip” one memory socket, filling only the dark gray sockets (you will have to pay a little attention to the sockets, since the dark gray and black sockets are very close in color).

ASUS X99-AFigure 4: Memory sockets; install four or eight modules for the best performance

[nextpage title=”On Board Peripherals”]

The Intel X99 chipset is a single-chip solution, which is also known as a PCH (Platform Controller Hub). This chip supports ten SATA-600 ports (there are no SATA-300 ports), supporting RAID (0, 1, 10, and 5).

The ASUS X99-A offers those ten SATA-600 ports (two of them are shared with a SATA Express connector). All SATA ports are located at the motherboard’s edge and rotated 90 degrees, so that video cards will not block them.

ASUS X99-AFigure 5: SATA Express and SATA-600 ports

The Intel X99 chipset supports eight USB 2.0 ports and six USB 3.0 ports. The ASUS X99-A offers those eight USB 2.0 ports, four soldered on the rear panel and four available through two headers located on the motherboard. It also supports ten USB 3.0 ports, six soldered on the motherboard rear panel (five of them controlled by one ASMedia ASM1074 chip and one ASMedia ASM1042 chip) and four available through two headers on the motherboard.

The ASUS X99-A doesn’t support Thunderbolt or Firewire ports. (There is a header labeled “TB_HEADER” to route digital audio to an optional Thunderbolt expansion card from ASUS.)

This motherboard supports 7.1+2 audio format, i.e., eight channels plus two independent channels for audio streaming. On this motherboard, the audio is generated by the chipset using the Realtek ALC1150 codec, which is an excellent audio codec, providing 115 dB signal-to-noise ratio for the analog outputs, 104 dB signal-to-noise ratio for the analog inputs, and up to 192 kHz sampling rate for both inputs and outputs, with 24-bit resolution. These specifications are good even for the user who wants to work professionally capturing and editing analog audio (e.g., converting LPs to CDs or MP3, converting VHS to DVDs or any other digital format, etc.).

The analog audio outputs are independent and the motherboard also comes with an on-board optical SPDIF output. It also has a header labeled “SPDIF_OUT”, where you can install an adapter to have a coaxial SPDIF output or to connect a cable to older video cards that required a physical connection to have audio on their HDMI outputs.

The analog audio outputs are independent only if you use a 5.1 analog speaker set. If you install a 7.1 analog speaker set, you will need to use the “line in” jack.

The portrayed motherboard has one Gigabit Ethernet port, controlled by an Intel i218V chip.

This motherboard comes with a “BIOS Flashback” button on the rear panel that allows the user to update the BIOS even with no CPU or memory installed: just insert a flash drive containing the BIOS file on a USB port, press the button for three seconds, and the BIOS will be flashed.

In Figure 6, you can see the motherboard rear panel, with the “BIOS Flashback” button, one shared PS/2 connector for mouse or keyboard, four USB 2.0 ports, six USB 3.0 ports, one Gigabit Ethernet port, one optical SPDIF output, and the analog audio jacks.

ASUS X99-AFigure 6: motherboard rear panel

[nextpage title=”Other Features”]

The portrayed motherboard supports the installation of a TPM (Trusted Platform Module), in charge of storing encryption keys in order to increase the security of the computer.

This X99-A has a POST diagnostics display that shows through a two-digit code which component is preventing the computer from turning on. It also has power and reset buttons, as shown in Figure 7.

ASUS X99-AFigure 7: POST diagnostics display and buttons

There is a “TPU switch” that enables an automatic overclocking, increasing the CPU clock multiplier (position “I”) or both the CPU clock multiplier and the CPU base clock (position “II”), and an “EPU switch” that enables or disables a power-saving feature. There are also one switch that configures the SLI or CrossFireX mode, and an “EZ_XMP switch,” which increases memory clock.

There is also a “MemOK!” button, which allows you to test the compatibility of the memory modules that are installed.

One curious fact is that the small heatsink near the rear panel has no function except aesthetics. As shown in Figure 8 (with the heatsink removed from its original place), the heatsink does not touch any component.

ASUS X99-AFigure 8: fake heatsink

In Figure 9, you can see the other accessories that come with the ASUS X99-A.

ASUS X99-AFigure 9: accessories

[nextpage title=”Voltage Regulator”]

The CPU voltage regulator circuit of the ASUS X99-A has eight phases for the CPU. The voltage regulator is controlled by an ASUS DIGI+ ASP1257 chip, using a digital design. Each phase makes use of one NTMFD4C85N integrated circuit.

ASUS X99-AFigure 10: Voltage regulator circuit

The ASUS X99-A uses solid electrolytic capacitors with a 5,000-hour life-span, twice the amount presented by regular solid capacitors. All coils on this motherboard are ferrite-core models, which can provide up to 20% improvement in efficiency.

If you want to learn more about the voltage regulator circuit, please read our tutorial on the subject.

[nextpage title=”Overclocking Options”]

The portrayed motherboard has several overclocking options. Below, we list the most important ones (0216 BIOS):

  • CPU Base Clock: from 80.00 MHz to 300.00 MHz in 0.1 MHz increments
  • CPU Core Voltage: from 1.000 V to 2.000 V in 0.003125 V increments
  • CPU Cache Voltage: from 1.000 V to 2.000 V in 0.003125 V increments
  • System Agent Voltage: from 0.800 V to 2.000 V in 0.003125 V increments
  • CPU Input Voltage: from 0.800 V to 2.700 V in 0.010 V increments
  • Memory Voltage: from 0.800 V to 1.900 V in 0.010 V increments
  • Chipset (PCH) Core Voltage: from 0.700 V to 1.800 in 0.00625 V increments
  • Chipset (PCH) I/O Voltage: from 1.200 V to 2.200 V in 0.00625 V increments
  • VCCIO CPU 1.05V Voltage: from 0.700 V to 1.800 V in 0.00625 V increments
  • VCCIO PCH 1.05V Voltage: from 0.700 V to 1.800 V in 0.00625 V increments
  • VTTDDR Voltage: From 0.200 V to 1.000 V in 0.00625 V increments
  • PLL Termination Voltage: From 0.200 V to 2.193804 V in 0.006602 V increments

ASUS X99-AFigure 11: overclocking options

ASUS X99-AFigure 12: voltage options

ASUS X99-AFigure 13: memory timings adjusts

ASUS X99-AFigure 14: memory timings adjusts

ASUS X99-AFigure 15: memory timings adjusts

[nextpage title=”Main Specifications”]

The main specifications for the ASUS X99-A include:

  • Socket: LGA2011-v3
  • Chipset: Intel X99
  • Super I/O: Nuvoton NCT6791D
  • Parallel ATA: none
  • Serial ATA: ten SATA-600 ports controlled by the chipset (RAID 0, 1, 10, and 5), supporting one SATA Express connector
  • External SATA: none
  • USB 2.0: eight USB 2.0 ports, four on the motherboard real panel and four available through two headers on the motherboard
  • USB 3.0: ten USB 3.0 ports, six on the motherboard rear panel (one controlled by the chipset, five controlled by one ASMedia ASM1042 chip and one ASMedia ASM1074 chip) and four available through two headers on the motherboard, controlled by the chipset
  • FireWire (IEEE 1394): none
  • Thunderbolt: none
  • On-board video: no
  • On-board audio: produced by the chipset together with a Realtek ALC1150 codec (7.1+2 channels, 24-bit resolution, 192 kHz sampling rate, 115 dB SNR for the outputs, and 104 dB SNR for the inputs), on-board optical SPDIF output
  • On-board LAN: one Gigabit Ethernet port, controlled by an Intel i218V chip
  • Wireless LAN: no
  • Buzzer: no
  • Infrared interface: no
  • Power supply required: EPS12V
  • Slots: three PCI Express 3.0/2.0 x16 slots (working at x16/x16/x8 on a 40-lane CPU or x16/x8/x4 with a 28-lane CPU), one PCI Express 2.0 x16 (working at x4 or x1), two PCI Express x1 slots, and one M.2 PCI Express x4 slot
  • Memory: eight DDR4-DIMM sockets (up to DDR4-3200, 64 GiB maximum)
  • Fan connectors: two four-pin connectors for the CPU cooler, and four four-pin connectors for auxiliary fans
  • Extra features: support for TPM, POST status display, and power and reset buttons
  • Number of CDs/DVDs provided: one
  • Programs included: motherboard utilities
  • More Information: https://www.asus.com
  • Average price in the U.S.*: USD 275.00

* Researched at Newegg.com on the day we published this article.

[nextpage title=”Conclusions”]

The ASUS X99-A is a good basic motherboard for socket LGA2011-v3 systems. It lacks a high-end PCI Express x16 slot configuration, with a PLX chip to automatically switch bandwidth to the slots that are requiring it; but this feature is only needed if you plan to build a very high-end gaming system with more than three video cards in SLI or CrossFireX configuration, which is not common.

The storage configuration is good, even with no extra SATA-600 ports, since the ten ports provided by the chipset are more than enough even for hard-core enthusiasts.

The highlights of this motherboard are the audio section, which uses a high-end codec with an excellent signal-to-noise ratio, the presense of one SATA Express connector, and the price, which is lower than high-end products for the same platform.

The only drawback we see with this motherboard is the lack of an M.2 slot compatible with SATA modules, since the M.2 slot offered is only compatible with PCI Express M.2 modules.