Energy Saving Functions Lack C1E
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|
|Pentium D||900 Series||B1||X||X|
|Pentium 4||6x1 Series||B1||X||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|