So, let’s start with the read speed that changes so impressively:

The difference is pretty big. You should remember, however, the memory speed is not the only thing affecting the system performance here. The CPU speed and processor bus frequency that were set at relatively high equal values and remained unchanged, as well as the type of the graphics card installed also influence the result. So, the negative effect from the slow memory subsystem was not so evident, but still noticeable, as in the following two tests:

There is hardly any difference at all in some cases, especially when the processor or graphics card speed determine the results.

However, sometimes Intel P965 based platform would run even slower than MSI P35 Platinum after the performance drop at 448MHz.

The next diagram may explain a few things here. Memory latency of the Intel P965 based mainboard is pretty high, which cannot help affecting the result.