Platform Discussion: Intel 7205 With Dual DDR400
Before we began the overclocking tests of this system in our labs, we tested Intel’s well-known 850 platform, which we first used in our 3.6 GHz project. As the front side bus speed of the Rambus board is restricted to 150 MHz, we are limited to a maximum of 3450 MHz (150 MHz x 23 = 3450 MHz) with a 3.06 GHz Pentium 4. This speed was completely unacceptable, especially because increasing the FSB speed overclocks the AGP bus to nearly 75 MHz.
Our aim was always to build a completely stable system that is suitable for everyday use using the best components currently available. What’s more, our lab tests had showed that even Rambus memory (PC4200) overclocked to 600 MHz is no longer able to keep up with the Granite Bay dual channel solution (Intel 7205 chipset) at extremely high FSB speeds.
The platform for extreme overclocking : the Asus P4G8X with Intel 7205 chipset. As well as dual channel DDR400 support, this board has synchronous FSB and CPU speeds, as well as variable settings for the CPU.
Here is some information on our favorite component, the Asus P4G8X that we used for this exercise. It is stable at an effective FSB speed of 195 MHz, which comes close to the bandwidth of the forthcoming Springdale platform. (800 MHz FSB is a figure conjured up by Intel’s marketing department.) The main memory is also able to cope with this speed, thanks to the DDR400 CL2 modules that are now becoming available. For our purposes, we chose the Corsair XMS3200 V1.1, since the TwinMOS modules failed when tested with aggressive timings.
A particular benefit of the Asus P4G8X is that the FSB and memory speed are synchronous, while the AGP bus can be adjusted in incremental steps (asynchronously). In other words : even with extreme overclocking, the AGP and memory settings always remain within specification. There is therefore no problem using a professional AGP graphics card (like the 3D Labs Wildcat).
Faster than Rambus : dual DDR400 in CL2 mode beats even RDRAM at 533 MHz (PC1066).
Corsair vs. Twinmos : while Corsair is comfortable with 200 MHz in CL2 mode, the Twinmos modules give up.
