Clash Of The OC'd Titans: Athlon XP 2300+ vs. Pentium 4/3000

Tuning AMD & Intel CPUs In Practice, Continued

We equipped the Northbridge of the chipset with a cooling fan to ensure its safety.

The CPU element of the Intel Pentium 4 based on Socket 478.

A view of the test system with the Intel Pentium 4/3000.

A similar problem was found with the Intel platform: there are motherboards for the Pentium 4 based on socket 478, with DDR SDRAM as well as RDRAM support. Using a slow SDRAM (PC133) was out of the question. A motherboard with Rambus memory is unsuited to extreme increases in clock speed, for the simple reason that there is currently no board on the market that allows a high enough CPU core voltage (non-specification). Additionally, there's the problem of limited bus clock speed on boards with the Intel 850 chipset: when overclocking, the AGP bus speed increases in direct proportion to the Front Side Bus. The result: with an FSB of 137 MHz (required for a CPU clock of 3000 MHz), for example, the AGP bus runs at 90.5 MHz. At this clock speed, graphics cards with the GeForce 3 chip cannot be operated, which was the result of our tests. Cards with the GeForce 2 chip proved to be the exception - sometimes, they were even able to reach 100 MHz. Nevertheless, in the 3D category, the performance values of the older GeForce 2 cards are too low for the benchmark records. Because of this, we used an Intel 845D motherboard to reach the 3000 MHz record. In contrast to the Intel 850, the Intel 845D at 137 MHz FSB offers an almost standard AGP clock speed of 67.9 MHz.

The following table lists the FSB and AGP clock speeds.