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Automatically Overclocking SLI Memory

AM2: AMD Reinvents Itself
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The memory module is clocked via the memory speed divider, which is in turn set by the CPU, normally to a maximum of DDR2 800 with an FSB of 200 MHz. With SLI memory technology, the FSB (Hypertransport, or HTT) is increased, which combined with the standard divider, results in a higher clock speed. In this case, the CPU multiplier is reduced so that it doesn't get overclocked.

Standard:


200 MHz * 14x = 2800 MHz / 7 = 400

Overclocking:


254 MHz * 11x = 2800 MHz / 6 = 466

The protective mechanism that adjusts the memory speed downwards to get a maximum of DDR2 800 is still activated.

At 2.8 GHz, which corresponds to the clock speed of the FX-62, the divider can assume the following values:


DDR2 800: dividers 6 and 7
DDR2 667: dividers 8 and 9
DDR2 533: dividers 10 and 11
DDR2 400: dividers 12 and 13

The processor thinks that it's working with an FSB of 200 and therefore adjusts the divider downwards. However, the FSB is actually increased to 254 MHz, which, in combination with the multiplier of 6, results in a memory clock of 466 MHz (DDR2 933).

With the multiplier set to 11, the memory divider is not optimal. Despite the high FSB, a memory clock of only 465 MHz can be attained.

With a memory clock of DDR2 800, the memory dividers 6 and 7 are available. Through the CPU's protective mechanism, the divider is set to 6.

2800 / 6x = 466 MHz (DDR2-932)

When SLI memory is activated, the HTT is set to 254, and the SLI technology automatically decreases the CPU multiplier to 11.

Through this, the memory clock can be increased to 465 - the value cannot be set manually.
Summary
  1. The AMD Generation Comes Of Age
  2. New Socket AM2 With DDR2
  3. Memory Speed: Socket AM2 Vs. Socket 939
  4. Write Performance
  5. Write Performance, Continued
  6. Write Performance, Continued
  7. Memory Speed: AMD Vs. Intel
  8. Memory Speed: AMD Vs. Intel, Continued
  9. The Divider Problem
  10. DDR2 SLI Memory: 10.3 GB Per Second
  11. Automatically Overclocking SLI Memory
  12. Automatically Overclocking SLI Memory, Continued
  13. All New AM2 Processors
  14. The New Socket AM2 With 940 Pins
  15. New Retention Module Requires New Heatsink
  16. Low Dissipation Guaranteed
  17. New Energy-efficient Processors
  18. Heatsinks: Things Gets Louder, Continued
  19. Features: Virtualization And TCPA
  20. Price Comparison: AMD More Expensive Than Intel
  21. Motherboards
  22. Gigabyte
  23. Epox
  24. The New nForce5 Chipset For AM2
  25. LAN Interface With 2 Gbit/s
  26. Test Setup
  27. Benchmarks And Settings
  28. Benchmarks Socket 939 Vs. Socket AM2
  29. Games - DirectX
  30. Games - DirectX, Continued
  31. Video
  32. Video, Continued
  33. Video, Continued
  34. Video, Continued
  35. Audio
  36. Applications
  37. Applications, Continued
  38. Applications, Continued
  39. Multitasking, Continued
  40. Synthetic Benchmarks
  41. Synthetic Benchmarks, Continued
  42. Synthetic Benchmarks, Continued
  43. Synthetic Benchmarks, Continued
  44. Synthetic Benchmarks, Continued
  45. Evaluating The Benchmark Scores
  46. Athlon 64 X2: Now Somewhat Slower
  47. Benchmarks AMD Vs. Intel
  48. Games - DirectX
  49. Games - DirectX, Continued
  50. Video, Continued
  51. Audio
  52. Applications
  53. Applications, Continued
  54. Multitasking
  55. Synthetic Benchmarks
  56. Synthetic Benchmarks, Continued
  57. Synthetic Benchmarks, Continued
  58. Synthetic Benchmarks, Continued
  59. Synthetic Benchmarks, Continued
  60. Synthetic Benchmarks, Continued
  61. AMD Athlon 64 FX-62 Vs. Intel Extreme Edition 965
  62. Conclusion: Good Energy Efficiency, But A Bad Value For Money
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