How Is Breaking The 4 GHz Barrier Possible?
A closer look at the processing cores in the 805 CPU reveals that the device is fabricated with a B0 product code (stepping). The first core in the 800 series on which this CPU is based was fabricated using the older A0 version instead.
The first items Intel fabricated in the 800 series were delivered with A0 version cores
The successor series used the B0 version cores, and this is the series to which the Pentium D 805 cores belong.
There aren't any significant differences between the two versions when it comes to energy saving functions or instruction sets, but it's easy to recognize from the B0 version that the Pentium D 805 really belongs to the second production series for this CPU. The motivation for a version update usually comes from further optimizations to the circuit layout or fabrication process, as well as corrections for design or behaviour errors. On all counts, the B0 version is an improvement over the older A0 version. Since this version could handle CPU clock rates of 3.2 GHz at the beginning of the series without any problems, a consequence of these improvements is that all B0 version CPUs should be able to handle CPU clock rates of at least 3.2 GHz. This was the theory we formulated before we started testing the Pentium D 805.
|Processor||Clock Rate||Version||sSpec Number|
|Pentium D 840||3.20 GHz||A0||SL88R|
|Pentium D 830||3.00 GHz||A0||SL88S|
|Pentium D 820||2.80 GHz||A0||SL88T|
|Pentium D 840||3.20 GHz||B0||SL8CM|
|Pentium D 830||3.00 GHz||B0||SL8CN|
|Pentium D 820||2.80 GHz||B0||SL8CP|
|Pentium D 805||2.66 GHz||B0||SL8ZH|