|It's not about clock speed, it's about efficiency. The P4 was a highly inefficient CPU & had to be run at extremely high clock speeds to get any work done. Even so, it was almost always beaten by AMD CPUs which ran at much lower clock speeds. That's because AMD CPUs are much more efficient. The Pentium D is based on the P4 therefore it suffers from the same inefficiency.|
The P3 was actually a more efficient CPU but Intel bailed on it in favor of the P4 design. After being embarassed by the performance numbers & heat related problems of the P4, Intel went back to the drawing & came up with a new design...the Core 2 Duo. The Core architecture used in the C2D is loosely based on the P3 design & is MUCH more efficient than the P4's Netburst architecture. In other words, Intel abandoned the P4 architecture & went back to where they probably should have stayed all long.
Did you check the link I posted in response #1? If not, have a look. The Pentium D at 3.4GHz rates only slighty better (3 points) than a Core 2 Duo at 1.66GHz.
Do NOT wasted your money on an outdated/inefficient Pentium D...either get a Core 2 Duo or build an AMD system.