Sunday, October 24, 2010

ECS P55H-AK: P55/NF200 Versus X58 In 3-Way SLI







We’ve seen how three-way SLI boosts gaming performance, but do we really need X58's PCI Express connectivity to realize those gains? Using three GTX 480s, we pit the latest P55/NF200 solution from ECS against a powerful X58-based incumbent to find out.
Captain Obvious dictates that, in order to properly support three graphics cards, your motherboard needs three PCIe x16 slots. Boards with three slots have been available at multiple price points for several generations. The problem with most of those boards was that the third slot was limited to only four PCIe 1.0 lanes. Nvidia would never allow such a low-bandwidth slot to support SLI because the card in the slowest slot often dragged down the performance of every other card in the array.

This is where enthusiasts might scream for a chipset with 48 PCI Express 2.0 lanes to support three graphics cards at full bandwidth from the primary controller. Unfortunately, no such product exists (though AMD comes close). Our own tests have shown that x8 mode is not much of a hindrance to SLI performance on Nvidia’s fastest cards, since CPU bottlenecks come into play long before a PCIe 2.0 x8 slot is completely tapped-out.
So, is the real requirement of three-way SLI really something as simple as a chipset that has 24 direct pathways? While many of our readers recommend X58-based motherboards to their friends specifically for the platform's 36 PCIe 2.0 pathways, we didn’t say that those lanes all had to come from a PCI Express controller. Long ago, Nvidia figured out that, since every card in an SLI array uses the same data, repeating data is an easy way to feed two graphics cards with the full 16 lanes of bandwidth from a chipset that supports only one x16 card. Nvidia calls this method “broadcast” and began using it several years ago to convert its low-cost 750a SLI chipset into a multi-card-supporting monster.
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This bridge has since been used on everything from its 680i to Intel’s X58, opening three-way SLI to a broad customer base. Today we consider one such motherboard that allows buyers of mainstream LGA 1156 processor buyers to seek the ultimate level of features and graphics performance, and see how it compares to an LGA 1366 alternative.


Dual SATA 6Gb/s and USB 3.0 controllers, a slew of PCIe 2.0 pathways, and three-way SLI are features found only among a small group of elite motherboards, yet many readers thought they’d never see a product of that elite group from the company Elitegroup. ECS is announcing its third assault on the enthusiast market in a big way with its P55H-AK.
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The previously-mentioned Nvidia NF200 bridge duplicates the data from the CPU's sixteen-lane PCIe 2.0 controller to 32 PCIe pathways, feeding three slots in x16-x8-x8 transfer modes. Duplicate data also explains why an SLI'ed set of three 1.5 GB cards has only 1.5 GB of total addressable memory.
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The LGA 1156 platform’s PCIe limitations don’t end there, though. All eight of the P55's PCIe lanes are limited to v.1.1-generation transfers. Like a few of its competitors, ECS has multiplexed these using a second PCIe bridge to provide true PCIe 2.0 transfers to a few onboard devices.

The PLX PEX8608 connects two NECD720200F1 USB 3.0, two 88SE9128 SATA 6Gb/s, and two RTL8111E gigabit networking controllers to the P55 PCH. Though all of these controllers must share the chipset’s 20 Gb pathway with other onboard devices, ECS knows that even high-end programs rarely push the limits of multiple controllers simultaneously.

The rear panel exposes two of the P55H-AK’s four USB 3.0 ports. ECS takes the unusual step of adding striping and mirroring capabilities to the nearby eSATA 6Gb/s ports.

Additional USB 3.0 connectivity is provided via the new front-panel interface recently validated in our own labs.

ECS P55H-AK Basic O/C Settings
BIOS Versionv.1.0 (08-04-2010)
CPU Core -.090 to +0.945 Volts (15 mV), 100-600 MHz BCLK (1 MHz)
CPU IMC -0.80 to +0.63 Volts (10 mV), 16x-18x BCLK (2x)
Memory -0.8 to +0.63 Volts (10 mV), 3x-6x BCLK (1x)
Memory TimingtCL 3-15, tRCD 3-15, tRP 3-15, tRAS 9-63 Cycles (1c)
Chipset -0.8 to +0.63 Volts PCH

The P55H-AK has a wide range of voltage settings and a high-enough frequency ceiling to assure that the overclocking limits of nearly any LGA 1156 processor can be reached.

Though the BIOS menu of the P55H-AK is advanced from ECS’ previous high-end attempts, it’s still a little basic compared to its hardcore competitors. Little items, such as having to set the “Performance Level” to Enhanced just to unlock multiplier controls are somewhat annoying.

Simplicity can be a good thing for beginners however, and we certainly found enough adjustments to set up our processor just the way we wanted. DRAM, for example, was changed to DDR3-1600 at CAS 7-7-7-21, using a 200 MHz BCLK to reach a CPU clock of 4 GHz.

A 1.38 V setting allows our Core i7-870 to run happily at 4 GHz at low heat, producing an actual voltage of approximately 1.36 V. A 14-phase voltage regulator keeps the system extra stable, just in case we need more.

ECS includes three flexible SLI bridges, allowing builders to configure three-way SLI by using the longer bridge to cross the other two bridges at the center card. The extra-important front-panel USB 3.0 breakout plate is also included, along with a slot-panel adapter for those who prefer more connections out back.



Looking through our broad range of X58 motherboard samples, the closest “fair fight” match was MSI’s Big Bang-XPower.
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With 36 total PCIe 2.0 lanes, the X58 chipset supports the same graphics card configurations as the P55+NF200 competition, but without the need for PCIe bridges. MSI divides 32 lanes across two primary PCIe 2.0 x16 slots, and further divides those pathways to remaining slots, allowing an exact x16-x8-x8 match to the P55+NF200 combo in today’s comparison.
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The Big Bang-XPower has fewer USB 3.0 and SATA 6Gb/s ports than today’s P55 competitor, but the tradeoff is advanced overclocking features that include a beefier voltage regulator. That higher-capacity voltage regulator will help to keep the higher-current CPU we’re using today stable at the same 4 GHz overclocked CPU frequency.

While both systems benefit from the same 4 GHz CPU clock, DDR3-1600 memory rate, and CAS 7-7-7-21 timings, the X58’s triple-channel memory controller increases the amount of installed memory to 6 GB using the same 2 GB modules. This is still a fair comparison however, since our games show no noticeable benefit from the increased capacity and bandwidth.

Not seen in the benchmarks is the additional power required to run the older Core i7-920 at 4 GHz, with higher voltage levels that are required to keep it stable at that frequency.

Additional information about the Big Bang-XPower can be found in its full review.

Extreme details make Alien Vs. Predator one of the few games that can take advantage of multiple high-end graphics processors at medium resolutions. We already see the advantage of three-way SLI at our lowest test setting, and even more surprising is the P55+NF200 lead.



CPU bottlenecks become less of an issue as we push towards GPU limits. Just as surprising as the P55 win at middle resolutions is the X58’s win at high resolutions, since GPU “bottlenecks” should be far more restrictive than platform differences.
Possible reasons for the X58 platform’s win include its triple-channel memory controller, the slight latency increase caused by adding an NF200 bridge mid-stream on the P55 motherboard, or both.

Even at 4 GHz, our Core i7 processors fail to keep pace with a pair of GTX 480s in DiRT 2.



As with Crysis, increasing our resolution to 2560x1600 shifts DiRT 2 load limits to the GPU, where three-way SLI begins to pay off. The P55 with NF200 bridge edges out the X58 in this title.

With four different lighting effects often producing four vastly different benchmark results, the combined score in the Call of Pripyat benchmark can be held back by either the CPU or GPU. Our 1680x1050 results certainly look promising for the P55+NF200 three-way SLI configuration, but the big advantages for triple-cards really come at higher settings.



The NF200-enhanced P55 remains in the lead at 2560x1600, even when AA is enabled.

Few readers will build a system specifically for a single game from our specific benchmark set, so a look at average performance differences can help.

With connectivity shortcoming addressed by the NF200 PCIe bridge, the P55 solution edges out the X58 at 1680x1050. This is an important win, since the X58 motherboard lacked the need for such latency-producing devices and was further enhanced by both its triple-channel memory controller and 2 GB of extra RAM.

The P55 with NF200 continues its slight lead through 1920x1080.

The X58 finally wins at 2560x1600, an important resolution for anyone who might also be considering a step up to triple-display Nvidia Surround because its four-megapixel size is similar to that of three 1280x1024 monitors.

A chart that combines resolutions might not be important to readers who have specific settings in mind, but average performance is half of the equation for upcoming efficiency calculations.

LGA 1156 processors tend to be somewhat more miserly than their LGA 1366 counterparts, and our particular configurations even saw lower voltage levels required to overclock with the smaller socket. Yet, Nvidia’s PCIe 2.0 bridge consumes some power, and that could lead to some interesting power consumption results.

Indeed, the P55+NF200 combination required more power in SLI than its X58 counterpart. We thought it might be close, but never expected the X58 to win this measurement.

Putting the above readings on a percent scale allows us to compare average power consumption to average performance for an efficiency calculation.

Lower power use in single-card mode gives the P55+NF200 platform a slight lead over its X58 rival, but we really doubt that anyone would buy an NF200-equipped board for a single card. The X58 takes a noticeable win in dual-card trim, but the P55 with NF200 manages a minor comeback with three cards installed.

The P55H-AK motherboard proves that even the fastest three-way SLI configurations need not suffer for the LGA 1156 platform’s shortage of PCIe 2.0 lanes, thanks to its inclusion of Nvidia’s NF200 bridge. With performance that usually matches and occasionally beats that of a similarly-priced X58 solution, this motherboard opens up a broader range of high-performance, high-efficiency, and cost-effective processors.
Inclusion of a second PCIe 2.0 bridge allows the P55H-AK to support several high-speed devices, including two SATA 6Gb/s and two USB 3.0 controllers over a 20 Gb shared connection, and the board even comes with a USB 3.0 front panel adapter bay. Yet, most surprising of all might be that this $300 product comes from ECS, a company long known for its budget-oriented, limited-feature products.
The P55H-AK is probably the boldest move ECS has ever made towards entry into the enthusiast market, but its success could depend on the company’s ability to overcome a most difficult task: changing the minds of buyers who are already committed to their favorite brand is a tall order. But as the sun sets on many of ECS' competitors, we can only wish the best of luck to every firm that takes up this task.







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