Gigabyte 990FXA-UD3 Motherboard

[nextpage title=”Introduction”]

Let’s take a look at the Gigabyte 990FXA-UD3, a mid-range socket AM3+ motherboard for AMD FX processors, based on the 990FX chipset. Let’s see what this motherboard has to offer.

The AMD 990FX chipset is basically an AMD 890FX chipset with a new name and supports the higher HyperTransport 3.0 speeds (up to 10.4 GB/s a.k.a. 5.2 GT/s) that weren’t used before and are supported by the FX processors from AMD.

So far, Gigabyte has launched four different motherboard models based on the AMD 990FX chipset; we list the differences between them in the table below. Prices were researched at Newegg.com on the day we published this article.

Specification	990FXA-D3	990FXA-UD3	990FXA-UD5	990FXA-UD7
Form Factor	ATX	ATX	ATX	E-ATX
Memory Sockets	4	4	4	4
PCI Express x16 2.0	4 (x16/x16/x4/x4)	4 (x16/x16/x4/x4)	5 (x16/x16/x0/x4/x4 or x16/x8/x8/x4/x4)	6 (x16/x16/x0/x0/x4/x4 or x16/x8/x0/x8/x4/x4 or x8/x8/x8/x8/x4/x4)
PCI Express x1 2.0	2	2	1	0
Standard PCI	1	1	1	1
CrossFireX	Yes	Yes	Yes	Yes
SLI	Yes	Yes	Yes	Yes
SATA-300	0	0	0	0
SATA-600	6	6	8	8
eSATA-300	0	0	0	0
eSATA-600	0	2	2	2
USB 2.0	14	14	14	14
USB 3.0	2	4	4	4
FireWire	0	2	2	2
Gigabit Ethernet	1	1	1	1
Audio	ALC889	ALC889	ALC889	ALC889
Voltage Regulator	4+1	8+2	8+2	8+2
Price	NA	USD 138	USD 170	NA

You can see the Gigabyte 990FXA-UD3 motherboard in Figure 1.

Figure 1: Gigabyte 990FXA-UD3 motherboard

[nextpage title=”Slots”]

The Gigabyte 990FXA-UD3 comes with four PCI Express 2.0 x16 slots, two PCI Express 2.0 x1 slots, and one PCI slot.

Two of the PCI Express x16 slots (PCIEX16_1 and PCIEX16_2) always work at x16 speed, and the other two slots (PCIEX4_1 and PCIEX4_2) always work at x4. Therefore, when installing two video cards, place them in the first (PCIEX16_1) and third (PCIEX16_2) slots for best performance.

If you plan to install a dual-slot video card in the fourth PCI Express x16 slot (PCIEX4_2), you will have to buy a case with at least eight slots. (Computer cases usually have seven.)

When installing dual-slot video cards, you “kill” the slot immediately to the left of the slot being used (looking at the motherboard with its rear connectors facing up). This means that you can’t install a dual-slot video card in the second (PCIEX4_1) PCI Express x16 slot, because you will block the third (PCIEX16_2) slot, which is faster than the second. Therefore, even though this motherboard has four PCI Express x16 slots, only three of them can be used with dual-slot video cards.

The first and the third PCI Express x16 slots support both SLI and CrossFireX technologies.

Figure 2: Slots

[nextpage title=”Memory Support”]

AMD CPUs have an embedded memory controller, meaning that it is the processor, not the chipset, that 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 AM3+ processors supports DDR3 memories up to 1,600 MHz.  According to Gigabyte, the 990FXA-UD3 supports memories up to 1,866 MHz.

The Gigabyte 990FXA-UD3 has four memory sockets. According to Gigabyte, this motherboard supports up to 32 GiB if you use four 8 GiB modules.

In order to enable the dual-channel mode, you must install two or four memory modules. On the Gigabyte 990FXA-UD3, all memory sockets are black. When installing two memory modules, you will have to skip one socket, i.e., you must install one module in the first socket and the other module in the third socket (and not in the second one).

Figure 3: Memory sockets; install two or four modules for the best performance

[nextpage title=”On Board Peripherals”]

The AMD 990FX chipset is a two-chip solution, and it is combined with the SB950 south bridge chip. The SB950 chip has six SATA-600 ports, supporting RAID (0, 1, 10, and 5). This motherboard has two additional eSATA-600 ports, controlled by a Marvell 88SE9172 chip (supporting RAID 0 and 1).

The SATA ports are installed on the motherboard edge and rotated 90°, so the installation of video cards won’t block them.

Figure 4: The six SATA-600 ports controlled by the chipset

The AMD 990FX chipset supports 14 USB 2.0 ports and the Gigabyte 990FXA-UD3 offers all 14 USB 2.0 ports, eight located on the rear panel and six available through three headers located on the motherboard. It also offers four USB 3.0 ports, two on the motherboard rear panel and two available through a header on the motherboard. The USB 3.0 ports are controlled by an EtronTech EJ168 chip.

The Gigabyte 990FXA-UD3 has two FireWire ports, one available on the motherboard rear panel and one available through a header. These ports are controlled by a VIA VT6308 chip.

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 a Realtek ALC889 codec, which is an outstanding solution, providing an impressive 108 dB signal-to-noise ratio for the analog outputs, 106 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. This means you are able to capture and edit analog audio (e.g., converting LPs to CDs or MP3, converting VHS to DVDs or any other digital format, etc.) with this motherboard without adding any background noise.

The motherboard has on-board optical SPDIF output. There is also a header for SPDIF signal on the motherboard, so you can install a coaxial output or connect it to a video card in order to have digital sound on the HDMI output.

The analog outputs are independent, meaning that you don’t need to share any of them when using a 7.1 analog speaker set.

The portrayed motherboard has one Gigabit Ethernet port, controlled by a Realtek RTL8111F chip.

In Figure 5, you can see the motherboard rear panel with a shared PS/2 connector for keyboard and mouse, optical SPDIF audio output, eight USB 2.0 ports, one FireWire port, two eSATA-600 ports, two USB 3.0 ports, one Gigabit Ethernet port, and the analog audio jacks.

Figure 5: Motherboard rear panel

[nextpage title=”Other Features”]

The Gigabyte 990FXA-UD3 has two BIOS chips, so if the main BIOS chip is corrupted by a virus or a bad BIOS upgrade, you can still recover the motherboard.

Figure 6: Two BIOS chips

As you can see, it has a legacy serial port, which is available through a header labeled “COMA.” You will need to buy an adapter if you want to use this port.

In Figure 7, you can see all of the accessories that come with the Gigabyte 990FXA-UD3.

Figure 7: Accessories

[nextpage title=”Voltage Regulator”]

The CPU voltage regulator circuit of the Gigabyte 990FXA-UD3 has eight phases for the CPU main voltage (VDD a.k.a. Vcore) and two for the CPU VDDNB (integrated memory controller, HyperTransport interface controller, and L3 memory cache) voltage. Therefore, it uses an “8+2” configuration.

The voltage regulator is shown in Figure 8.

Figure 8: Voltage regulator circuit

The Gigabyte 990FXA-UD3 uses solid electrolytic 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 (FC BIOS):

• Base clock: From 200 MHz to 500 MHz in 1 MHz increments
• CPU core voltage: Offset from -0.800 V to +0.775 V in 0.025 V increments
• CPU NB (memory controller) voltage: Offset from -0.800 V to +0.775 V in 0.025 V increments
• Memory voltage: From 1.024 V to 2.135 V in 0.005 V increments
• HyperTransport voltage: From 0.725 V to 1.835 V in 0.005 V increments
• PCI Express PLL voltage: From 1.325 V to 2.435 V in 0.005 V increments
• CPU PLL voltage: From 2.025 V to 3.135 V in 0.005 V increments
• Chipset NB voltage: From 0.865 V to 1.735 V in 0.005 V increments

Figure 9: Overclocking options

Figure 10: Voltage settings

Figure 11: Memory timings

Figure 12: Memory timings

[nextpage title=”Main Specifications”]

The main specifications for the Gigabyte 990FXA-UD3 include:

• Socket: AM3+
• Chipset: AMD 990FX + SB950 
• Super I/O: ITE IT8728F
• Parallel ATA: None
• Serial ATA: Six SATA-600 ports controlled by the chipset (RAID 0, 1, 10, and 5)
• External SATA: Two eSATA-600 ports controlled by a Marvell 88SE9172 chip (RAID 0 and 1)
• USB 2.0: 14 USB 2.0 ports, eight on the rear panel and six available through three headers on the motherboard
• USB 3.0: Four USB 3.0 ports, two on the rear panel and two available through one headers; controlled by an EtronTech EJ168A chip
• FireWire (IEEE 1394): Two ports, one on the rear panel and one available through a header; controlled by a VIA VT6308P chip
• On-board video: No
• On-board audio: Produced by the chipset together with a Realtek ALC889 codec (7.1+2 channels, 24-bit resolution, 192 kHz sampling rate, 108 dB SNR for the outputs, and 106 dB SNR for the inputs), on-board optical SPDIF connector
• On-board LAN: One Gigabit Ethernet port controlled by a Realtek RTL8111F chip
• Buzzer: No
• Infrared interface: Yes
• Power supply required: EPS12V
• Slots: Four PCI Express 2.0 x16 slots (working at x16/x4/x16/x4), two PCI Express 2.0 x1 slots, and one PCI slot
• Memory: Four DDR3-DIMM sockets (up to DDR3-1866, 32 GiB maximum)
• Fan connectors: One four-pin connector for the CPU cooler, one four-pin connector for an auxiliary fan, and two three-pin connectors for auxiliary fans
• Extra features: Two BIOS chips
• Number of CDs/DVDs provided: One
• Programs included: Motherboard utilities
• More Information: https://www.gigabyte.com
• Average Price in the U.S.*: USD 138.00

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

[nextpage title=”Conclusions”]

If you are looking for a mainstream socket AM3+ motherboard based on the high-end chipset 990FX, the Gigabyte 990FXA-UD3 may be an excellent option. It comes with six SATA-600 ports, four USB 3.0 ports, and four PCI Express x16 slots supporting both two-way SLI and CrossFireX.

One other highlight of this motherboard is the excellent audio codec (108 dB SNR for the outputs and 106 dB SNR for the inputs).

If you want to build a gaming or multimedia PC based on the AMD FX processor, and don’t need fancy features like lots of extra SATA-600 or USB 3.0 ports, the Gigabyte 990FXA-UD3 is a good choice, since you can save some bucks to invest on a more powerful video card.