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Energy Saving Functions Lack C1E

A 4.1 GHz Dual Core at $130 - Can it be True?
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By deactivating the C1E energy-saving function in the Pentium D 805, Intel bursts any hope of achieving the same functionality as the Intel Pentium Extreme Edition 965 with 266 MHz FSB. This makes it impossible to use a BIOS modification to achieve an "Enhanced Halt State" and thereby to raise the CPU multiplier any higher than 14x. This would have been an ideal configuration had it been possible: 14 x 266 = 3.73 GHz.

Restricted functionality means that only NX and Thermal Monitor 2 may be activated in the BIOS.

You can believe what the programs tell you. Although C1E is recognized, it can't be activated.

To be sure of our results, we put this CPU into various motherboards from Asus and Gigabyte. This let us test a variety of situations in which we could attempt to activate the C1E function. None of the motherboards with the most current BIOS versions would let us turn it on, however.

Intel's decision to turn the C1E function off is important for two reasons:

  • All previous desktop CPUs with the C1E function couldn't lower their clock rates below 2.8 GHz. In the case of the Pentium D 805, its standard clock rate of 2.66 GHz sits well below this threshold. A C1E function would limit the device to no less than 1.86 GHz, which is an atypical value for Intel's desktop CPUs.
  • Intel itself may have realized that this chip possesses extraordinary overclocking potential, and thus nearly the same performance as a fast Extreme Edition that costs over $1,000, In that case, it would have the same clock rate as the Intel Pentium EE 965 (14 x 266). Naturally, the Pentium D 805 only has half the L2 cache and no Hyper Threading, though.

Because the C1E function isn't present, this CPU also doesn't support SpeedStep. That's because these two functions are mutually interdependent.

Energy saving functions
CPU Name Version C1E EIST TM1 TM2
Pentium EE 965 C1 X X
Pentium EE 955 B1 X
Pentium D 900 Series B1 X X
Pentium 4 6x1 Series B1 X X
Pentium EE 840 A0 X X
Pentium D 805 B0 X
Pentium D 800 Series B0 X X X
Pentium D 800 Series A0 X X X
Pentium EE 3.72 GHz N0 X
Pentium 4 6x0 Series N0 X X X
Pentium 4 5x1 Series D0, E0 X X
Pentium 4 5x0J Series D0, E0 X X
Pentium 4 5x0 Series D0, E0 X X
Pentium EE 3.46 GHz M0 X
Pentium EE 3.40 GHz M0 X
Save Power Protection
Summary
  1. A Budget CPU At Top Speeds
  2. A Budget CPU At Top Speeds, Continued
  3. Inside the Pentium D 805
  4. The Secret Of The Multiplier
  5. 133 MHz FSB: Perfect For Overclocking
  6. How Is Breaking The 4 GHz Barrier Possible?
  7. How Is Breaking The 4 GHz Barrier Possible? Continued
  8. How Is Breaking The 4 GHz Barrier Possible? Continued
  9. Three Theories Where The Customer Comes Out Ahead
  10. Which Memory Clock Speed Is Most Suitable?
  11. The Right Chipset
  12. Keeping Cool When Power Consumed Tops 150 Watts at 4.1 GHz
  13. Keeping Cool When Power Consumed Tops 150 Watts at 4.1 GHz, Continued
  14. Power Consumption Levels Top 200 W
  15. Power Consumption Levels Top 200 W, Continued
  16. Energy Saving Functions Lack C1E
  17. Risk-free Overclocking, Including Heat Protection
  18. Ready For The 64 Bit Future
  19. Tom's Hardware Guides Overclocking Diary
  20. 3.33 GHz Remains Stable At Standard Voltage Levels
  21. 3.33 GHz Remains Stable At Standard Voltage Levels, Continued
  22. Trouble Free Operation At 3.60 GHz
  23. At 3.8 GHz Some Minor Voltage Increases Become Necessary
  24. Water Cooling Is Recommended For 4.0 GHz
  25. Water Cooling Is Recommended For 4.0 GHz, Continued
  26. Overclocking To 4.10 GHz Boosts Basic Clock Speed By 54 Percent
  27. Overclocking To 4.10 GHz Boosts Basic Clock Speed By 54 Percent, Continued
  28. Will The System Boot At 4.3 GHz?
  29. Benchmark Results Show Performance Increases Of Up To 54 Percent
  30. 3D, Continued
  31. 3D, Continued
  32. Video Editing / Video Encoding
  33. Video, Continued
  34. Video, Continued
  35. Audio Encoding
  36. Office Applications
  37. Office Applications, Continued
  38. Parallel Applications - Multitasking
  39. Synthetic Benchmarks
  40. Synthetic Benchmarks, Continued
  41. Synthetic Benchmarks, Continued
  42. Synthetic Benchmarks, Continued
  43. Summary Overview: Who's The Winner?
  44. Conclusion: The 4.1 GHz Dual Core Delivers Peak Performance For Pocket Change
  45. Conclusion, Continued
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