iXBT Labs - Computer Hardware in Detail






Gigabyte P55A-UD6 Motherboard

A fine example of the company's new LGA1156 series.

April 12, 2010

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As you probably know, Gigabyte is now primarily focused on the LGA1156 platform. It is no coincidence that the company offers a lot of such motherboards. There are 22 products on the P55 chipset alone. Another 7 are based on FDI-enabled chipsets, making use of graphics cores integrated into dual-core processors for this platform. Obviously, the latter series is primarily aimed at low and mid-end markets. While the abundance of motherboards based on the high-end chipset is created by both older P55 series and newer P55A series (with SATA 6Gb/s and USB 3.0 support). Note that the company updated its product line considerably, having fixed a number of issues, both real and imaginary. For example, the platform has often been criticized for being able to support just two graphics cards in a x8+x8 configuration. But you shouldn't forget that only a minority of users have two graphics cards, and not many of those have high-end models for which x8+x8 is not enough. Anyway, Gigabyte considered these complaints as well. Thanks to the NVIDIA nForce 200 SLI processor, the top-class P55A-UD7, has four PCIe x16 slots which can be used as x16+x16, x16+x8+x8 or x8+x8+x8+x8, depending on how many graphics cards you have. Note that all of the long slots use CPU's PCIe lanes, so the chipset lanes are allocated to the only PCIe x1 slots (the 5th already) and a bunch of peripheral controllers. In other words, the use of nForce 200 solved the issue of insufficient PCIe lanes typical for models of the older series. As a result, P55A-UD6, unlike its predecessor, has ceased to be the highest-end motherboard in the series, but it offers both advanced features and reasonable design updates. In general, the newer motherboard won't be criticized as much, though it still belongs to the top-end segment where users are quite hard to please.


We didn't expect P55A-UD6 and P55-UD6 to be that different. The latter had initially been designed to feature SATA 6Gb/s as well and was bereft of that feature at the last moment. It would seem Gigabyte could just return to the initial design. But they preferred a more complex, but also a more reasonable approach.

Firstly, they changed the socket manufacturer from Foxconn to LOTES. Why? Well, there was a tempest in a teapot a few months ago -- turned out Foxconn sockets could malfunction, helping extremely overclocked CPUs to expire. And since users of top-class motherboards often overclock their CPUs, motherboard makers angrily refused to have anything to do with Foxconn products and declared they'd use LOTES sockets that had no such problem.

That didn't go without a scandal as the first P55A samples had Foxconn sockets but LOTES covers. No surprise though, as the fuss was kicked up when those motherboards were almost ready to be shipped. There was enough time for those to come into the spotlight. Besides, some partners had already received samples as well. Obviously, that instigated another scandal, Gigabyte-related this time. Like, the company was swindling users, selling non-overclocker sockets as overclocker ones. But the truth was that only a minor quantity of motherboards of the first series was affected, of which only a small amount was actually sold. While the majority of motherboards both looked and performed as was promised.

Anyway, this improvement will only be appreciated by those who use extremely overclocked processors all the time. The mainstream market will do (and already does) fine with Foxconn sockets. Low and mid-end motherboards from Gigabyte and other vendors come equipped with those exactly.

Moving on, there's one improvement that is quite useful. Many users have used to complain about insufficient power supplied over USB in all of its implementations. While 500mA is more than enough for mice, keyboards, webcams, etc., there are devices that could use more. These include portable hard drives, for example, which are usually connected to two USB ports by means of a splitter cable. Also included is charging mobile gadgets over USB. In the latter case higher current strength is not necessary but desirable. E.g., most smartphones can be charged from 1A current, with bundled adapters, while charging over USB takes twice as much time.

Having offered USB 3.0, the industry bent before the users' wishes and increased the current strength from 500mA to 900mA. Gigabyte went even further and offered the 3x USB Power Boost feature that provided 1.5A over USB 2.0 and 2.7A over USB 3.0. Can is result in compatibility issues? No, it cannot. Stability is guaranteed, given the current is strong enough. If the current strength is higher than needed, the excessive amperage just won't be used. In other words, devices requiring 500mA will consume as much, while those in need of 800mA, for example, will still be powered over a single USB port, not two like before. So, this is the first advantage of the new motherboards.

The second advantage will be noticed by the owners of passive USB hubs. For example, each port of a 4-port bus-powered hub, connected to a regular USB port, will only provide a bit more than 100 mA. This may be insufficient even for some flash drives and keyboards with backlights. But connected to a USB port of a new Gigabyte motherboard, each port will provide about 400mA -- enough even for some portable hard drives. If you connect the same hub to a USB 3.0 port, you'll get almost 700mA per port which is definitely enough.

We tested this in practice by means of an Apacer PH151 hub and a bunch of portable drives we have lying around in our lab. We could power two HDDs from a single USB 2.0 port. Using a blue USB 3.0 port, we easily powered all four HDDs we could connect to the hub.

Of course, features like this come at a price. So probably some users will complain that they have lived fine without that fancy Power Boost, using right hard drives and active hubs. Well, turns out that you don't have to pay for what you don't use. The company offers different products for different target audiences. The top-class motherboards based on P55 support 333 Onboard Acceleration (SATA 3.0, USB 3.0 and 3x USB Power Boost) for the most demanding users. If you would like USB 3.0 support, but at a lower price, there are motherboards based on P55, H55 or H57 with matching additional controllers. These only provide increased current strength over two USB 3.0 ports, while chipset ports supply the regular 500mA. And if you want to save even more, there are older motherboards based on P55, and a few new ones based on H55, that only have previous-generation features. In other words, nothing prevents you from buying an Ultra Durable 3 motherboard without new interfaces and other novelties.

The aforementioned new interfaces are the key difference of P55A from the previous P55 series. P55A-UD6 is a fine example, demonstrating platform's benefits and drawbacks. One benefit is that LGA1156 allows building machines ranging from entry-level to top-class. While drawbacks, or rather one major drawback, come into the light in the top-end segment. We're talking about the insufficient number of PCIe that forces to make compromises to improve functionality. It affected the previous series, and, sadly, it affects this one as well. (With the exception of P55A-UD7.) In particular, one "pool" of 4 chipset lanes of Gigabyte P55A-UD6 can be allocated as follows:

  • 1 to each PCIe, 1 to eSATA controller. Results in 3 x PCIe x1 and eSATA.
  • All to the lower PCIe x16 slot that will work as x4. Disables 2 x PCIe x1 and eSATA.

It's not good to lose two eSATA connectors. All the more so that their implementation is as close to perfect as it can be: eSATA ports are combined with USB, letting you connect certain flash drives or portable HDDs by means of a single cable. They should've let us disable one of the LAN controllers instead. On the other hand, you may need to use a hardware RAID controller to turn your PC into a server. Dual LAN interfaces would certainly come in handy in this case. Anyway, LAN controllers utilize another pool of 4 lanes (P55 supports 8 lanes in total) also shared with USB 3.0 and SATA 6Gb/s. Or those can feed on another source -- a controller built into CPU (if the second graphics slot is not used) -- as can SATA 6Gb/s, USB 3.0, or both.

Graphics slots can also work in various configurations:

  • The first slot works in the x16 mode, the second is not used, additional controllers use chipset lanes.
  • Both slots work in the x8 mode (e.g., if two graphics cards are used), additional controllers use chipset lanes.
  • The first slot works in the x8 mode, the second is not used, USB 3.0 and SATA 6Gb/s controllers are handled by CPU.

Put together, all of the above can be really confusing. Does it have to be that complicated? Theoretically, it does. The matter is that the PCIe 2.0 controller of P55 PCH actually provides just 250MB/s of bandwidth (the same as PCIe 1.x). This isn't enough for USB 3.0, let alone SATA 6Gb/s with its 600MB/s bandwidth per port. However, CPU's controller actually corresponds to the PCIe 2.0 specifications and offers 500MB/s per lane. This isn't perfect, but much better nevertheless.

Whether you need a bandwidth that high or not is up to you. At least Gigabyte offers you a choice.

One company that can be criticized is Intel. They could've implemented at least 17 lanes to make x16+x1 configurations possible. The way things are now, installing any card into the second graphics slot automatically switches the first slot to the x8 mode. Or that extra lane could've been used for another controller. From this angle, the platform offered by AMD looks much more balanced. It seems that the drawbacks of LGA1156 will only be fixed in the next chipset series that will feature faster interaction of PCH and CPU, meaning chipset's PCIe controller will probably also perform better. Perhaps, they'll add more PCH lanes as well. But that chipset series will only be rolled out in almost a year, so, for now, you'll have to think thrice and configure once or choose LGA1366 or AM3 that have no such problems.

This concludes the description of what is new in P55A-UD6. Naturally, additional controllers need to be tested and we've done that, so stay tuned for a dedicated review. In other aspects the new motherboard resembles P55-UD6, so if you're interested in the CPU power circuitry or cooling system, please read that review.

There's just one more thing to clarify. What's the difference between P55A-UD6-C and P55A-UD6 models? (Or P55-UD6-C and P55-UD6?) Motherboards with the "C" suffix have Smart TPM disabled. Smart TPM means hardware data encryption with 2048-bit key. Another unique feature is that one can lock protected data remotely by means of a Bluetooth mobile phone. Sounds nice, but the free use of encryption technologies is forbidden in many countries. So Gigabyte had to disable Smart TPM (and add the "C" suffix) to sell its motherboards somehow in those parts of the world.

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