Tuesday, October 12, 2010

Gaming Across Three Screens: GTX 460, GTX 480, And Quad-SLI


Display spanning is quickly becoming the high-mark for serious gaming machines of all budgets, with more powerful cards allowing higher resolutions. Yet, as panel resolutions higher than 1080p become harder to find, do we really need more than two cards?

AMD calls it Eyefinity. Nvidia calls it Surround. Whatever you call it, spanning a game across three displays sets the PC industry up as the champion of realism years after naysayers pointed to the lower cost of gaming consoles. You can keep your four-year-old platform. This is all about pushing the high-end; that's something consoles, by design, simply cannot do toward the end of their protracted lives.

It turns out that people really can see more than what’s in front of them, and those who are able to see things sneaking up from the side have a huge advantage over those who cannot.

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Everyone who can afford a decent gaming PC can supposedly get in on this action, thanks to huge advances in GPU technology that have made mid-market cards a viable solution for ultra-wide resolutions. The biggest question is how much quality you’ll need to sacrifice to get a smooth frame rate.

Nvidia has its own requirements to satisfy, since two cards are required to connect three screens, but two midrange cards like the GeForce GTX 460 can certainly stand up to any high-end model.

Seeking the highest graphics detail levels in our games, we started out with a pair of GeForce GTX 480s for today’s test. GeForce GTX 460 cards were added to address mid-budget concerns, and we even added a second pair of GeForce GTX 480s to address those seeking the highest possible resolutions. With so many configurations at our disposal, we’re ready to answer the question “How much GPU do you really need to game across multiple displays?”


Few motherboards are able to support Quad-SLI due cost and space constraints. Nvidia requires two of its NF200 PCIe bridges to enable SLI across four cards, and four of its double-slot cards would require a larger-than-standard eight-slot case.

Many motherboard manufacturers place an oversized chipset cooler into the uppermost one or two slot positions of each high-end model, forcing circuit board design of an even grander scale. Gigabyte’s X58A-UD9 fits all those criteria, for better and for worse.

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It’s fortunate that Gigabyte’s competitor Foxconn had the forethought to push its Ultra ATX proposal to the forefront at CES 2008. Over a dozen ten-slot cases followed that push. While Ultra ATX never became an official standard, the cases are still available. It’s equally unfortunate that etailers list neither “Ultra ATX” nor the slot count in product search engines, forcing buyers to sort through dozens of oversized case models to find a suitable ten-slot solution.

Yes, we get all of the toys. Too bad that we don't get the play time. Reference-class cards made up our two-, three-, and four-way SLI GeForce GTX 480 configurations.

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Originally used in our GeForce GTX 460 SLI scaling article, Sparkle’s 700 MHz cards represent the lower-cost alternative. Because the GTX 460 has only one bridge connector, it’s limited to a two-way SLI configuration.

Intel’s Core i7-980X is the most powerful CPU in our arsenal, yet even it isn’t strong enough to provide optimal gaming results when paired with more than a single GTX 480. We thus ditched its powerful boxed cooler and used an even larger unit as we clocked it to 4.00 GHz.

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The Cogage True Spirit is powerful, yet its mid-speed fan still didn’t get us to the level of cooling we desired. To further increase cooling without adding noise, we substituted a 38 mm-thick model from NMB.

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We set Kingston’s KHX16000D3ULT1K3/6GX to DDR3-1600 CAS 7 to achieve optimal performance without boosting CPU uncore voltage.

Test System Configuration
CPUIntel Core i7-980X (3.33 GHz, 12 MB Cache)
Overclocked to 4.00 GHz at +100 mV, 160 MHz BCLK
MotherboardGigabyte X58A-UD9 BIOS F3 (05/28/2010)
Intel X58 Express, LGA 1366
RAMKingston KHX16000D3ULT1K3/6GX (6 GB)
DDR3-2000 at DDR3-1600 CAS 7-7-7-21
GTX 480 GraphicsMSI GeForce GTX 480 1.5 GB
700 MHz GPU, GDDR5-3696, two-way, three-way, and four-way SLI
GTX 460 GraphicsSparkle GeForce GTX 460 1 GB
700 MHz GPU, GDDR5-3600, two-way SLI
Hard DriveWestern Digital Velociraptor WD3000HLFS, 300 GB
10 000 RPM, SATA 3Gb/s, 16 MB cache
SoundIntegrated HD Audio
NetworkIntegrated Gigabit Networking
PowerOCZ-Z1000 1,000 W Modular
ATX12V v2.2, EPS12V, 80 PLUS Gold
Software
OSMicrosoft Windows 7 Ultimate 64-bit
GeForce GraphicsForceWare 258.96
ChipsetIntel INF 9.1.1.1020


The filled platform looks ready-to-rumble, even before we added its drives and power supply.

The most controversial component will certainly be OCZ’s Z1000 modular power supply. Independently verified to deliver 1000 W at 89% efficiency, the controversy stems from its inability to support four cards natively, as it’s only wired to support three. It also lacks the 1200 W rating we would normally recommend as a minimum for four of these cards when using a lesser processor.


Originally intended for a three-way article, putting the Z1000 in a four-way configuration could make up for the lost coverage, so long as the unit survives today’s particularly harsh treatment. We got around its shortage of power connectors by adding a 6-pin splitter plus a 4-pin to 6-pin adapter (two things we don’t recommend to our readers). Our feeling is that if this unit can tolerate today’s four-way SLI test, it should at least be recommendable for any three-way SLI, single-CPU configuration.

Nvidia states that every monitor in a surround configuration must be capable of the same resolution and timings, but that's not the whole story. No combination of the four monitors we originally attempted to use would span successfully, in spite of that fact that each was capable of displaying 1080p at 60Hz. In the end, we had to track down three completely identical monitors for today's test. Many readers facing a similar situation will thus be forced to buy a complete set of three new monitors to replace their non-matching, outdated models.

We searched the Web for the best price-per-inch and found that a new crop of 1600x900 displays is displacing 1280x1024 in value, with prices starting at around $100 per panel. The 1680x1050 and 1920x1200 resolutions have both been displaced by 1920x1080 (1080p), starting at around $160 per panel. Since our 1600x900 and 1920x1080 resolutions were both designed for 16:9 displays, we added 1280x720 (720p) as an FPS-boosting alternative setting.

Benchmark Configuration
3D Games
Aliens Vs. Predator BenchmarkAlien vs Predator Benchmark Tool
Test Set 1: Highest Settings, No AA
Test Set 2: Highest Settings, 4x AA
Call of Duty: Modern Warfare 2Campaign, Act III, Second Sun (45 sec. FRAPS)
Test Set 1: Highest Settings, No AA
Test Set 2: Highest Settings, 4x AA
CrysisPatch 1.2.1, DirectX 10, 64-bit executable, benchmark tool
Test Set 1: Highest Quality, No AA
Test Set 2: Highest Quality, 4x AA
DiRT 2Run with -benchmark example_benchmark.xml
Test Set 1: Highest Settings, No AA
Test Set 2: Highest Settings, 4x AA
S.T.A.L.K.E.R.: Call Of PripyatCall Of Pripyat Benchmark version
Test Set 1: Highest Settings, No AA
Test Set 2: Highest Settings, 4x MSAA
Synthetic Benchmarks and Settings
3DMark VantageVersion: 1.0.1, GPU and CPU scores


The latest CoD variation has fairly impressive visuals for a DX9 game, but DX9 is less hardware-intense than DX11.

Even a pair of GeForce GTX 460 graphics cards is overkill for this game, and even when the game is spanned across three 1080p monitors. We expect Nvidia will notice this, and use this title to prove the ability of lesser cards to support an “immersive gaming experience.” It is the second best-selling game of all time in the US, after all.


Crysis has been known, since the day of its release, as an frame rate demolisher, and we’ve kept it around just to see if anything is ever capable of pushing its limits.

With results like these, we really had to look to the game’s minimum FPS to get a clear idea of which resolutions are supported by what hardware.

The good news for mid-budget gamers is that spanning across three 720p displays is possible with a pair of GeForce GTX 460 cards, with the higher 4x AA test reading a minimum 26 FPS. The cheaper cards even pull a playable 21 FPS minimum across three 1600x900 monitors with AA disabled.

Two GeForce GTX 480 units span three 1080p displays at a minimum of 22 FPS with AA disabled, but enabling AA at that resolution requires quad-SLI.

Extra cards require additional system resources, but the first solid indication of a problem for quad SLI appears at our lowest S.T.A.L.K.E.R. benchmark test setting. From there, increased details burden the cards more than the CPU, and the quad SLI configuration pulls ahead.

Two GTX 460 cards play the game smoothly at all resolutions, but only with AA disabled. Three-way GTX 480 SLI pulls a minimum of 19 FPS in the Sun Shafts test at our highest test setting, so that configuration is probably playable. Anyone who wants to be completely sure their system can play every possible setting in every possible lighting condition will want to step up to quad-SLI.

While there were two special cases where only a set of four GeForce GTX 480 cards in quad-SLI would suffice, there was one game where even a pair of GTX 460 cards would push smooth frame rates to our test limit. For those willing to forgo AA modes at the maximum quality settings of Crysis and S.T.A.L.K.E.R.: Call of Pripyat, a comparison of average frame rates could be helpful.

The best news for mid-budget buyers is that the GeForce GTX 460 SLI solution is generally acceptable for spanning three 720p displays, allowing added visual immersion at the cost of some granularity.

Even with a triplet of 1600x900 monitors, the cheapest solution in today’s test is usually good enough.

AA kills the cheapest solution when using three 1080p monitors, yet two GTX 480 cards are a viable option at most settings. We should remind readers of to the two games mentioned at the top of this page, where the combination of AA mode, maximum settings, and maximum resolution require four cards.

Against our own advice, we used a 1000 W power supply in today’s four-way SLI tests. How much power did we really need?

Manufacture-specified TDP aside, it appears that our power supply actually needed 282 W per GeForce GTX 480 graphics card. Yet, pushing our power supply beyond its rated limit caused the four-way configuration to pull 1364 W (rather than 1316 W), dropping our power supply’s efficiency from its rated 89% to 85%. That means the maximum continuous output power we demanded of OCZ’s Z1000 power unit was 1164 W, a full 16% beyond its rating. Bravo OCZ!

Putting power consumption on a percent scale allows us to more easily calculate relative efficiency. We based our comparison on the GTX 480 SLI configuration, where GTX 460 SLI represents the lower-energy alternative.

Putting aside special circumstances where the four-way SLI configuration took a commanding lead, its overall performance looks worse than that of three-way SLI.

Efficiency is a comparison of work done to power used, calculated by dividing the above two charts. This would have normally resulted in a 100% score for the baseline configuration.

Because there really is no such thing as 100% efficiency in the computer industry, we subtracted “1” from the results in the above chart to show only the efficiency differences. As the above chart shows, a third card uses enough energy to lose 6% in efficiency, in spite of its 29% performance gain.

Looking at the average performance charts, one might be deceived into believing that four-way SLI is a dud. The truth is somewhat murkier however, as our maximum settings for two games required four-way SLI to achieve smooth game play. The problem is consistency, as it appears that CPU overhead has reduced the configuration’s maximum frame rate under moderate graphics load in a way that really hurts any analysis of average performance.

At the other end of the price spectrum, anyone who doesn’t require anti-aliasing will find the GeForce GTX 460 SLI configuration suitable for playing nearly any game across three 1600x900 displays. Some games can successfully be expanded to triple 1920x1080 displays using these cards, while others can handle the middle resolution with AA enabled.

In the middle, two GTX 480 graphics cards can handle three 1920x1080 displays, but occasionally require AA to be disabled. The added performance of three-way SLI, though signficant, is rarely a barrier-breaker.

Our biggest disappointment came from the monitors themselves. Playing at 1080p across three monitors is akin to sighting your enemy through a gun slit. Gaming aficionado Chris Angelini voiced an interest in large 4:3 displays, but this editor can’t think of any that are large enough to separate forward vision from peripheral vision.

Perhaps a triplet of 1920x1200 displays would be the best compromise, but the 16:10 aspect ratio is becoming difficult to find. Anyone who completely agrees with that assessment might want to take a small risk with a trio of these mid-quality units while they’re still available.

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