P67, X58, And NF200: The Best Platform For CrossFire And SLI

Intel’s flagship X58 chipset supports three-way SLI and triple-channel RAM, while its fastest gaming processor is stuck with a far less-capable P67 platform. With multiple GPU installations hanging in the balance, which solution should you choose?

Tom's Hardware's Three-Part, 3-Way Graphics Scaling Series

Part 1, The Cards: Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI

Part 2, The Slots: GeForce And Radeon On Intel's P67: PCIe Scaling Explored

Part 3, The Chipsets: P67, X58, And NF200: The Best Platform For CrossFire And SLI

The advantages and shortcomings of Intel’s mainstream platforms are well-known to anyone who follows technology. A total of sixteen PCIe 2.0 lanes originating from the CPU reduce latency (good) and total available bandwidth (bad) compared to Intel’s high-end X58 chipset.

Fortunately, an unlocked multiplier on the K-series processors makes overclocking a piece of cake. On the other hand, though, the CPU also only supports two graphics cards for SLI configurations. That's actually a limitation imposed by Nvidia. Technically, P67 enables the processor's 16 lanes and trio of PCIe controllers.

Artificial roadblocks aside, those limitations allow Intel’s high-end X58 chipset to remain a top choice for extreme enthusiasts, given 36 PCIe 2.0 lanes supporting up to four graphics cards in x8 arrangements with four lanes to spare. Too bad unlocked multipliers for that platform are limited to very expensive Extreme Edition CPUs. But even still, overclocking via the base clock gives less expensive processors access to faster interface speeds. And of course, there's the benefit of a triple-channel memory controller, providing up to 50% more bandwidth than any of Intel’s mainstream solutions (even if the advantage is largely academic).

Part one of our this three-part series answered questions about multiple-GPU scaling, while part two addressed PCIe bandwidth needs for a single card. Tying it all together, today we’re going to determine whether a 32-lane (or greater) PCIe controller is really a requirement for dual- and triple-GPU arrays, whether triple-channel memory and twice the base clock can help a 4 GHz Core i7 CPU based on the Bloomfield design (an overclocked Core i7-920) overcome the architectural advancements of a 4 GHz Core i7 processor based on Sandy Bridge (an overclocked Core i7-2600K), and how much of a difference Nvidia’s lane-multiplying NF200 PCIe bridge makes when 16 or 32 lanes aren’t enough.

Any comparison between slightly-different platforms is sure to lead proponents of one side to scream bias against the other. These parts were carefully chosen to make this a fair fight, though.

For example, fans of the LGA 1155 interface will point out that by having triple-channel memory, X58 Express also has 50% greater memory capacity, so long as the modules are identical. But we'd argue that triple-channel (and the extra memory) is simply a missing feature from the closer-to-mainstream platform. Anyone standing up for their LGA 1366-based board will point out that the Core i7-990X is age-appropriate for this comparison, yet we’ve found that ultra-expensive six-core CPUs offer no performance advantage in games. While a different Bloomfield model might have allowed a closer price match, we would have still picked 20 x 200 MHz (Bloomfield) vs 40 x 100 MHz (Sandy Bridge) clock settings to squeeze the greatest performance from both processors at the resulting 4 GHz comparison frequency.

Test System Configuration
LGA 1155 CPU	Intel Core i7-2600K (Sandy Bridge) LGA 1155: 3.40-3.80 GHz, 8 MB L3 Cache, Overclocked to 4 GHz at 1.25 V
LGA 1366 CPU	Intel Core i7-920 (Bloomfield) LGA 1366: 2.66-2.93 GHz, 8 MB L3 Cache, Overclocked to 4 GHz at 1.40 V
P67 Motherboard	Asus P8P67 Pro: Intel P67 Express, LGA 1155, BIOS 1204 (01/27/2011)
P67+NF200 Motherboard	Asus P8P67 WS Revolution: Intel P67 Express, Nvidia NF200 PCIe Bridge, LGA 1155, BIOS 1007 (01/24/2011)
X58 Motherboard	Asus P6X58D-E: Intel X58 Express, LGA 1366, BIOS 0502 (01/17/2011)
X58+NF200 Motherboard	Asus P6X58-E WS: Intel X58 Express, Nvidia NF200 PCIe Bridge, LGA 1366, BIOS 05301 (02/22/2011)
RAM	Kingston HyperX T1 DDR3-2133 at DDR3-1600 CAS 7-7-7-21, 1.60 V 2 x 2 GB for Dual-Channel (LGA 1155), 3 x 2 GB for Triple-Channel (LGA 1366)
GeForce Graphics	Asus ENGTX570/2DI/1280MD5: 742 MHz GeForce GTX 570 GPU, 1.25 GB GDDR5-3800
Radeon Graphics	XFX HD-695A-CNFC: 800 MHz Radeon HD 6950 GPU, 2 GB GDDR5-5000
Hard Drive	Western Digital WD1002FBYS: 1 TB, 7200 RPM, SATA 3Gb/s, 32 MB cache
Sound	Integrated HD Audio
Network	Integrated Gigabit Networking
Power	OCZ-Z1000M: 1000W Modular, ATX12V v2.2, EPS12V, 80 PLUS Gold
Software
OS	Microsoft Windows 7 Ultimate 64-bit
GeForce Graphics	GeForce/Ion 266.58
Radeon Graphics	AMD Catalyst 11.1
Chipset	Intel INF 9.2.0.1019

While most of the above motherboards can be found in our previous reviews, Asus’ P6X58-E WS is new. The primary feature that differentiates it from the P6X58D-E is the addition of Nvidia’s NF200 PCIe bridge, which expands three-way CrossFire and SLI slot configurations from x16-x8-x8 to x16-x16-x16. Other important upgrades include the ability to support a total of five single-slot graphics cards, though single-slot cards will not be part of today’s tests.

By relying on a single brand of motherboard for all four samples, we reduce the risk that performance differences will be the result of BIOS or clock speed differences. Asus helped us keep the spotlight on its brand a little longer by sending along three of its GeForce GTX 570 graphics cards as well.

Of course we couldn’t let Nvidia’s cards stand alone. We borrowed our AMD Radeon HD 6950s from another project.

Benchmark Configuration
3D Games
Aliens Vs. Predator Benchmark	Alien vs Predator Benchmark Tool Test Set 1: Highest Settings, No AA Test Set 2: Highest Settings, 4x AA
Crysis	Patch 1.2.1, DirectX 10, 64-bit executable, benchmark tool Test Set 1: Highest Quality, No AA Test Set 2: Highest Quality, 4x AA
F1 2010	v1.01, Run with -benchmark example_benchmark.xml Test Set 1: Highest Settings, No AA Test Set 2: Highest Settings, 4x AA
Just Cause 2	Version 1.0.0.2, Built-In Benchmark "Concrete Jungle" Test Set 1: Highest Details, No AA, 16x AF Test Set 2: Highest Details, 4x AA, 16x AF
S.T.A.L.K.E.R.: Call Of Pripyat	Call Of Pripyat Benchmark version, all options, HDAO Test Set 1: Ultra Preset, DX11 EFDL, Ultra SSAO, No AA Test Set 2: Ultra Preset, DX11 EFDL, Ultra SSAO, 4x MSAA
Synthetic Benchmarks and Settings
3DMark 11	Version: 1.0.1.0, Benchmark Only