iXBT Labs - Computer Hardware in Detail






Gigabyte P55-UD6 Motherboard

The indiscreet charm of top-end boards.

October 19, 2009

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This motherboard is based on the Intel P55 chipset (the P55 bridge). You can read about its features in the corresponding review. The motherboard contains a lot of additional controllers to expand its basic functionality:

  • Integrated audio, based on the 10-channel (7.1+2) HDA codec Realtek ALC889 (top codec from this company supporting audio output from HD DVD and Blu-ray in full quality), 7.1-ch audio, front line-ins/outs, optical and coaxial S/PDIF-Out jacks on the rear panel, S/PDIF-Out to output sound via a graphics card with HDMI.
  • Two Gigabit network controllers (10/100/1000 Mbps) based on Realtek RTL8111DL (PCIe 1x) with a number of enterprise-level technologies.
  • IDE/SATA-II controller "Gigabyte SATA 2" (it's a remarked JMicron JMB363 with the PCIe 1x interface) supporting a single IDE (PATA) channel (for two devices), including CD/DVD drives, and two SATA300 ports.
  • Two SATA-II controllers JMicron JMB362 (PCIe 1x), one of which maintains the ninth and tenth onboard SATA300 ports, which the second is added for the Power eSATA connector (eSATA/USB Combo in Gigabyte terms) on the rear panel.
  • FireWire controller based on Texas Instruments TSB43AB23 (PCI) supporting three ports, two of which (6-pin and 4-pin) are installed on the rear panel, while the third is just a pin header on the PCB.

The GA-P55-UD6 stands out with its record-breaking number of SATA controllers even on the background of most top motherboards: There are four of them (including the one in the chipset), all of them supporting RAIDs and offering 12 SATA ports (10 internal and 2 external ones). This number of disk devices in a desktop computer is obviously a curiosity, but it has nothing to do with Gigabyte. This motherboard was initially planned to have six SATA300 ports and a couple of eSATA ports, while the other four internal ports should have supported SATA600. It had to contain two Marvell 88SE9123 controllers, one of them working in full force (to support two SATA600 and one PATA), the second one -- without PATA. That's exactly how the first samples of the GA-P55-UD6 were designed, sent to some reviewers this summer. But then the company found out that such chips might cause problems. Information about probability and conditions of their appearance varied greatly -- some people mentioned that only the PATA part worked inadequately, while the others reported about SATA problems as well. The chip manufacturer admitted these problems and promised to fix bugs in a new revision of the controller to be released by the end of this year. As a result, motherboard manufacturers decided against using this buggy controller -- and we support this decision. Anyway, there exist no devices on the market designed for SATA600 so far. Even if there had been any, their owners would have got no preference, because PCIe 1x throughput is actually insufficient even for the sterling operation of a single SATA300 channel, to say nothing of two SATA600 ones. However, people had already seen this motherboard with ten SATA connectors, so the company had to find a way out of this situation. Gigabyte just decided to install time-proven JMB362 and JMB363 instead of the questionable new controllers. Both of them are widespread (on motherboards from different manufacturers), and PATA implementation in the latter chip proved to be very good. It had absolutely no problems detecting an optical drive at startup and in Windows, allowing to boot from a CD, etc. So the manufacturer has kept almost all its initial promises -- this motherboard really supports a lot of hard drives, including a couple of PATA devices (which is especially important for motherboards on Intel chipsets, which have lacked this feature for a long time). And what concerns the lack of SATA600, frankly speaking, even if it had been implemented and Marvell 88SE9123 had demonstrated no problems, we would have still criticized it, because it would have been implemented for the sake of appearances (PCIe 1x bottleneck).

We should be grateful to engineers for their implementation of FireWire: most manufacturers currently use cheaper chips from VIA that cope well with storage drives, but sometimes having problems with miniDV cameras.

Realtek network controllers used in this motherboard can be united into a single two-gigabit interface (teaming), which should significantly increase system bandwidth in cases needing more than 1 Gbps. Moreover, a network driver balances the load in the teamed channel (to distribute the load evenly between both physical interfaces, if possible). When one of the ports (or cables) fails, all the traffic is routed to the other (channel throughput is halved in this case, of course) to avoid disconnecting clients from this server. Additional parameters of Realtek network controllers can be configured with a proprietary utility from this company.

What concerns the audio controller, it's impressively often used in modern top motherboards, easily catering to the needs of an average consumer. Realtek likes to mention HDCP support as one of its advantages, which allows to output audio to a graphics card (or any other expansion card) with HDMI. It's surely very convenient. However, this feature supports a limited number of formats -- it can output audio that can meet restrictions of the old SPDIF. That is multi-channel HD-audio is out of the question in this case: the best option is Dolby Digital/DTS. However, it's relevant only to those users, who already invested into the corresponding content and home cinema equipment, such as an expensive receiver (budget models for $300-$400 are equipped with much worse DACs than inexpensive sound cards). The other users will use the analog connection. Fortunately, the ALC889 can compete with SoundBlaster Live! 5.1, Audigy2, or even Creative PCI Express X-Fi Xtreme Audio that are sometimes installed into top motherboards. And now we publish audio test results in 16 bit, 44 kHz and 48 kHz modes using RightMark Audio Analyzer 6.0 and the Terratec DMX 6fire sound card.

Test 44 kHz 48 kHz
Frequency response (from 40 Hz to 15 kHz), dB: +0.01, -0.06 +0.01, -0.04
Noise level, dB (A): -93.5 -93.8
Dynamic range, dB (A): 93.4 93.7
THD, %: 0.0033 0.0032
Intermodulation distortion + Noise, %: 0.0066 0.0064
Channel crosstalk, dB: -93.5 -92.8
General performance: Excellent Excellent

As we can see, the results in both cases are not bad, even excellent (according to the program). These results are a tad better those of MSI P55-GD65 with the same codec (and the same chipset) that scored only "Very good". What's even more interesting, they are practically the same in both modes (44 kHz for AudioCD or compressed formats and 48 kHz for DVD Video). So it makes no sense for users of this audio solution to use software resampling, which was important for the old sound cards.

This rear panel looks perfect for a top motherboard manufactured in 2009. There are eight USB ports to satisfy even hard-driving users, so they will hardly want to install four additional ports on the rear panel. Their number grows to ten, if you don't need eSATA, which is sort of a new record for modern motherboards (unlike the 24-phase power supply, it's more justified from the practical usage point of view). However, the other motherboards with this number of "accessible" USB ports are also manufactured by Gigabyte.

If you need eSATA, you can use two ports of this type. Both ports are of the latest revision: with power supply sufficient for external hard drives or flash drives. Besides, the manufacturer hasn't forgotten about two FireWire ports of both types, so any cable will do. There is no need to install one additional FireWire and four USB ports on the rear panel -- they may come in handy only for a front panel of your PC enclosure or specific equipment, such as a built-in card reader. It's a pity that the standard set of brackets lacks the one with a COM port. However, those who need it will certainly find a way to solve this problem, while common users may not even know that such interfaces ever existed.

In other respects, everything is traditional -- two network ports and a full set of audio jacks typical of High-End motherboards. We can only welcome one combined PS/2 port instead of two separate ones: users of top motherboards will hardly possess both a mouse and a keyboard with this outdated interface. Mice have been converted to USB long ago. Keyboards have a longer service life, but this motherboard has a single port to accommodate one such device. One is better than nothing and better than two, because the freed space now houses two additional USB ports.


It makes no sense to conduct detailed tests of motherboards with processors with integrated memory controllers, as performance level is determined mostly by the CPU itself. Motherboards may differ only by memory timings and other tweaks. But in this case we can give an exhaustive answer on performance in the nominal mode -- that's exactly how we tested all three existing processors for LGA1156.


The only drawback of this motherboard is its redundancy. But this sin is shared by other top models as well. In case of the Gigabyte GA-P55-UD6, everything is elevated practically to the absolute. Unfortunately, it's harmful not only from the point of view of aesthetics, but in a more grounded sense as well: this model turns out to be one of the most expensive motherboards with the LGA1156 socket. If it had been the only motherboard in Gigabyte's product range, this company would have deserved admonition. However, it's one of eleven products for the new socket. If you need extended functionality solely for the nominal CPU mode, you should consider the GA-P55-UD5, which differs only by the 12-phase power circuit, four memory slots, and no LED indicator and on-board buttons. Another step lower (and 1.5 times as cheap) is the GA-P55-UD4, which has only two full-size PCIe slots, eight internal SATA ports, and no power for the external eSATA ports. Cheaper models gradually rid of additional controllers and other architectural addons, down to products for those users, who just need a good motherboard for the new processors without outstanding features for about $150, that is more than twice as cheap as this motherboard under review. So why the Gigabyte GA-P55-UD6? It looks like a perfect example of the principle "make it glossy no matter the cost". It's a perfect choice for users who want the ultimate motherboard. Or at least to dream about one. Besides, such models in product ranges of any manufacturer are necessary to show off their engineering skills to create bleeding-edge devices. Devices to amaze people.

Indeed, Gigabyte succeeded to do it here. We've seen many High-End motherboards, but the GA-P55-UD6 still managed to impress us. So engineering efforts (and the skill to combine incompatible things, such as LGA1156 and six memory slots) definitely deserve an award -- this motherboard really has an original design.

The motherboard provided by the manufacturer.

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Page 1: Introduction, design

Page 2: Package contents

Page 3: Features, conclusions

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