The same peak point should also apply if one has a 1.5 GHz processor and Radeon 7000, or a 4 GHz processor and Radeon X1800. It's the balance that matters. The performance graph is based on my system which is sort of balanced. Memory, the hard drive speed, and programs running in the background also play a factor. When doing the experiment I closed whatever I could to free up memory which meant that I had to go offline to free up 140 MB memory from Firefox (the big one) and other programs I had running. I took the fastest values I could.

In otherwords, stick to models of about 1500 to 5000 polygons for best results. I need to run an experiment to find the peak with more precision than in the graph. The graph just gives the full range and isn't focused on anything special, just the limits of DirectX (and rendering speed).

Note: I'm assuming "balanced" as in the card and processor being of the same release dates (as in when they were first available). I don't know when the first 3.0GHz processors were released, but they should be somewhere around August 2004, which is in the range my video card (Radeon 9600 XT) was released.