Breaking The Sound Barrier: The Pentium 4 With A 1 GHz FSB And DDR500
The leap from a 533 MHz to an 800 MHz FSB clock speed did wonders for the overall performance of Pentium 4 systems. After that development, high-end chipsets then saw launch that could accommodate two memory channels (dual channel) as well as DDR memory.
Memory producers, such as Buffalo and Corsair, then began to ante up by offering modules that accommodated up to 466 MHz speeds. Subsequently, more 500 MHz modules (PC4000 from Corsair, Kingston, and OCZ) became available. We then had the perfect excuse to set up a test system running at a tantalizing 1000 MHz clock speed.
The idea of "clean" FSB overclocking is far from new. "Clean" means the synchronous increase of FSB and main-memory clock speed. Even in the days of the Pentium II, mainboards existed that could operate at over 90 MHz, compared to the 66 MHz system speeds that were common at that time. Indeed, in percentage terms, the 25% to 50% speed raise was not significant.
It should not be forgotten, however, that the gulf between CPU speed and system speed has thus far been steadily increasing. To counter-affect this, the Pentium 4 bus is "quad-pumped," enabling it to transfer four times the amount of data per clock cycle. This means that with a FSB800 or 800 MHz system clock, an underlying clock speed of 200 MHz must be taken into account. This technology makes overclocking attempts all the more risky since there is simply no longer the scope for up to 50% faster clock speeds.
For a 1000 MHz FSB clock speed, 250 MHz serves as the underlying speed. This equates into an increase of 25%. We tested to see if the increased performance met the theoretical speed boost.