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Overclocking Potential

Besides its efficient cooler, the Sapphire Radeon HD 7870 OC could please us with its high overclocking potential. Its GPU was stable at 1240 MHz without our changing its voltage. The memory chips could be overclocked to 6080 MHz.

The overclocked card was 5°C hotter under load while the speed of its fans increased by 300 RPM.

We couldn’t reach a higher GPU clock rate even after increasing its voltage to 1.3 volts although many users achieved such overclocking results. Anyway, we guess our overclocking attempt at the default voltage was quite rewarding, too.

Testbed Configuration and Testing Methodology

All graphics cards were tested in a system with the following configuration:

The frequencies of the top Sapphire Radeon HD 7950 were adjusted to their nominal levels in order to check if the overclocked Sapphire Radeon HD 7870 will be able to catch up with a more expensive model. Asus GeForce GTX 560 Ti 448 Cores works at nominal frequencies by default:

 

In order to lower the dependence of the graphics cards performance on the overall platform speed, I overclocked our 32 nm six-core CPU with the multiplier set at 37x, BCLK frequency set at 125 MHz and “Load-Line Calibration” enabled to 4.625 GHz. The processor Vcore was increased to 1.455 V in the mainboard BIOS:

Hyper-Threading technology was enabled. 16 GB of system DDR3 memory worked at 2 GHz frequency with 9-10-10-28 timings and 1.65V voltage.

The test session started on May 20, 2012. All tests were performed in Microsoft Windows 7 Ultimate x64 SP1 with all critical updates as of that date and the following drivers:

We have already tested in detail AMD Radeon HD 7870 and HD 7850 that is why today we will test the new sapphire graphics card using a reduced-size testing suite only in only resolution of 1920x1080 pixels. The tests were performed in two image quality modes: “Quality+AF16x” – default texturing quality in the drivers with enabled 16x anisotropic filtering and “Quality+ AF16x+MSAA 4x” with enabled 16x anisotropic filtering and full screen 4x antialiasing. We enabled anisotropic filtering and full-screen anti-aliasing from the game settings. If the corresponding options were missing, we changed these settings in the Control Panels of Catalyst and GeForce drivers. We also disabled Vsync there. There were no other changes in the driver settings.

The list of games and applications used in this test session includes two popular semi-synthetic benchmarking suites, one technical demo and 3 most popular games of various genres:

  • 3DMark Vantage (DirectX 10) – version 1.0.2.1, Performance and Extreme profiles (only basic tests);
  • 3DMark 2011 (DirectX 11) – version 1.0.3.0, Performance and Extreme profiles;
  • Unigine Heaven Demo (DirectX 11) – version 3.0, maximum graphics quality settings, tessellation at “extreme”, AF16x, 1280x1024 resolution with MSAA and  1920x1080 with MSAA 8x;
  • Metro 2033: The Last Refuge (DirectX 10/11) - version 1.2, maximum graphics quality settings, official benchmark, “High” image quality settings; tesselation, DOF and MSAA4x disabled; AAA aliasing enabled, two consecutive runs of the “Frontline” scene;
  • Total War: Shogun 2 (DirectX 11) – version 2.0, built in benchmark (Sekigahara battle) at maximum graphics quality settings;
  • Crysis 2 (DirectX 11) – version 1.9, we used Adrenaline Crysis 2 Benchmark Tool v.1.0.1.13. BETA with “Ultra High” graphics quality profile and activated HD textures, two runs of a demo recorded on “Times Square” level.

If the game allowed recording the minimal fps readings, they were also added to the charts. We ran each game test or benchmark twice and took the best result for the diagrams, but only if the difference between them didn’t exceed 1%. If it did exceed 1%, we ran the tests at least one more time to achieve repeatability of results.

 
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