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Gigabyte’s P55A-UD6 stands out as the first roundup motherboard to support USB 3.0 and SATA 6.0 Gb/s. These two features were essentially free at the motherboard’s release, as the new model came at the same $250 list price as its predecessor. However, at the time this review was written, this newer version was actually cheaper than the earlier one, thanks to a limited-time $30 instant rebate at one of our favorite online vendors.
Users still get all the advanced features for which the UD6 and earlier DQ6 models are famous, in addition to the USB 3.0 and SATA 6.0 Gb/s controllers. Enhancements include dual-eSATA ports, dual-gigabit network controllers, dual-I/O panel FireWire, dual-format digital audio outputs, and active pathway switching for dual graphics cards. Like other recent Gigabyte boards, the eSATA ports have been co-opted with USB to supply USB-powered eSATA thumb drives, with an additional benefit that users can use the same jacks for either type of device.
A 24-phase CPU voltage regulator is designed to supply the smoothest power possible at high loads, while also being capable of powering-down unneeded phases at lower loads to increase efficiency.
Gone is the JBM363 controller Gigabyte once labeled GSATA, as the distance between Ultra ATA and eSATA ports would have caused engineering difficulties for a single controller. Gigabyte instead uses separate JMicron JMB362, ITE IT8213, and Marvell 88SE9128 controllers to support its eSATA, Ultra ATA, and SATA 6.0 Gb/s functions. Gigabyte’s use of three separate controllers is a plus compared to what Asus offers, which forces all of its third-party interfaces to use a single 2.5 Gb/s PCIe link.
Yet Gigabyte’s solution is far from perfect, as LGA 1156 platform limitations prevent any perfect solution from being developed. USB 3.0 requires a PCIe 2.0 link that the P55 Express chipset doesn’t provide, and a graphics card normally uses the 16 PCIe 2.0 pathways from the CPU. Builders must decide how valuable these features are, as enabling SATA 6.0 Gb/s forces a single graphics card to x8 mode, while running two graphics cards in the upper and middle slots makes the Turbo SATA3 and Turbo USB 3.0 functions non-selectable. Because we always test P55-based motherboards in either x16 or dual-graphics (CrossFire or SLI) modes, P55A-UD6's SATA 6.0 Gb/s and USB 3.0 functions have no place in a motherboard-performance comparison.
The P55A-UD6 also gains an x4-bandwidth/x16-length PCIe slot compared to the previously reviewed P55-UD4P. The newer interface could be used for lower-performance graphics applications or other medium-bandwidth devices, since the chipset doesn’t provide PCIe 2.0 mode to its four pathways. Both high-bandwidth PCIe slots have the same placement on both boards, with three spaces between them to assist airflow to double-slot graphics card coolers. Yet Gigabyte puts the top x16 slot in the second-from-top position, forcing all three long slots downward by one position and limiting the bottom four-lane slot to single-thickness cards. Meanwhile, a cooling sink limits the top x1 slot to 3.3” or shorter expansion cards.
Like any other LGA 1156 motherboard, the P55A-UD6 is limited to eight memory banks via the processor’s dual-channel DDR3 controller, so that typical high-end configurations of 8GB or 16GB are possible via four 2GB or 4GB modules. But Gigabyte has found a trick, a little slight-of-hand perhaps, to make it appear that the board supports more memory: by repeating the second bank from one side of the second memory channel to a third pair of DIMMs, users are able to populate the P55A-UD6 with up to four single-sided modules plus two single-sided or double-sided modules. The combination of six DIMMs and a large central sink makes the P55A-UD6 look like a pricier LGA 1366 solution. But the limitations of LGA 1156 still apply, with the installation of four double-sided modules preventing any use of the additional memory slots.
The P55A-UD6 MB Intelligent Tweaker menu shows basic system status, with several submenus providing additional information and controls.
The M.I.T. Current Status submenu doesn’t even indicate that the system is fully populated with RAM, listing modules by DIMM rather than bank.
The Advanced Frequency Settings submenu provides the frequency and ratio controls typically found on the main overclocking menu of competing products. Gigabyte adds a few drive strength and clock-skew controls compared to lower-market products.
The Advanced Voltage Settings submenu includes all the basic settings most users require to achieve a good overclock and adds DRAM reference voltage.
The Advanced Memory Timings submenu contains only a few basic settings in addition to separate submenus for Channel A and Channel B timings. Choosing the Quick option allows both channels to be set from the menu of a single channel.
Timings include all the basics and several advanced latencies, with automatic mode selectable for individual controls.
Pressing F11 and F12 keys in the BIOS main screen allows saving or restoring up to eight custom configurations as user profiles. These can also be exported to a drive, and the board even “remembers” a few of the recent configurations that a user might have forgotten to store as a profile.
The P55A-UD6 includes several booklets, but only four SATA cables. An eSATA breakout adapter reminds us of the days before these ports were added to Gigabyte’s I/O panel, and includes two eSATA-to-SATA data cables and a four-pin-to-dual-SATA power splitter. A single SLI bridge is also included.