The biggest problem we’ve encountered when using high-end graphics solutions is that at the highest resolutions and settings, the cards cannot get data fast enough from the CPU and RAM to keep their graphics cores busy. In an effort to reduce this so-called “CPU bottleneck,” we overclocked our Core i7 processor to 4.00 GHz at a 200 MHz base clock.
Test System Configuration
Intel Core i7 920 (2.66 GHz, 8.0 MB Cache)
Overclocked to 4.00 GHz (BCLK 200)
Swiftech Liquid Cooling: Apogee GTZ water block,
MCP-655b pump, and 3x120mm radiator
Intel X58/ICH10R Chipset, LGA-1366
6.0 GB Crucial DDR3-1600 Triple-Channel Kit
Overclocked to CAS 8-8-8-16
GTX 295 Graphics
2x GeForce GTX 295
2x 576 MHz GPU, GDDR3-1998
GTX 280 Graphics
3x EVGA GeForce GTX 280 PN: 01G-P3-1280-AR
602 MHz GPU, GDDR3-2214
Radeon HD 4870 X2 Graphics
2x Sapphire HD 4870 X2 PN: 100251SR
2x 750 MHz GPU, GDDR5-3600
Seagate Barracuda ST3500641AS
0.5 TB, 7,200 RPM, 16 MB Cache
Integrated HD Audio
Integrated Gigabit Networking
ATX12V v2.2. EPS12V, 850W, 64A combined +12V
LG GGC-H20LK 6X Blu-ray/HD DVD-ROM, 16X DVD±R
Microsoft Windows Vista Ultimate x64 SP1
NVidia Forceware 181.20 Beta
ATI 8.561.3.0000 Beta
Intel INF 22.214.171.1246
Cooling an overclocked Core i7 CPU isn’t a task for lightweights, so we added Swiftech’s latest Apogee GTZ water block to the liquid-cooling kit we normally use for motherboard testing.
Feeding data quickly to the CPU are three 2.0 GB DDR3-1600 modules from Crucial. These particular samples are part of an upcoming High-End Triple-Channel shootout; watch for it in a few days.
Including 3-way SLI tests required a motherboard with proper slot spacing. Gigabyte’s EX58-Extreme worked well on our open platform, though the third card does extend below the lowest slot on standard cases.
Our second card came from MSI; its N295GTX-M201792 arrived overclocked to 655MHz GPU with GDDR3-2100 memory. We actually had to underclock this card to 576MHz/GDDR3-2000 reference speeds to make it cooperate with our reference card in Quad SLI. MSI says it could be releasing an overclocked board soon, which we'll be anxiously awaiting.
Our GTX-295 graphics cards were set to reference clock speeds, so it made sense to use reference-speed HD 4870 X2s in an apples-to-apples comparison. Our cards came from Sapphire.
Finally, the GTX 280 sets the standard for judging GTX 295 performance improvements. We tested three reference-speed cards in single, SLI, and 3-way SLI.
Call of Duty: World at War
Patch 1.1, FRAPS/saved game
Patch 1.2.1, DirectX 10, 64-bit executable, benchmark tool
Far Cry 2
DirectX 10, Steam Version, in-game benchmark
Left 4 Dead
Very High Details, No AA / No AF, vsync off
World in Conflict
Patch 1009, DirectX 10, timedemo
3D Mark Vantage
Version 1.02: 3DMARK, GPU, CPU scores