System setup and notes
Here's a quick rundown of the test system should you wish to compare benchmark results with your own.- Intel Pentium 4 3.2GHz ES 800FSB CPU, run at 12x, 13x and 14x multipliers
- Corsair 1GByte TwinX Matched XMS4400 Memory (2 x 512MByte)
- ABIT IS7 i865PE Springdale (17 BIOS)
Other
pertinent hardware- Gainward GeForce FX 5700 Ultra 128MB (500/906)
- Scan 3XS-OC system
Software
- Windows XP
How to test RAM running at such a high frequency was the first question that required answering. An initial attempt was made on an ABIT IC7 Canterwood board and a semi-unlocked Intel Pentium 4 3.2GHz CPU. Dropping the multiplier down to 12x and raising the FSB seemed to work to around 265MHz. Serious instability set in that couldn't be attributed to the CPU. It was either a case of the chipset's or RAM's ceiling. That's where the difficulty sets in, that is, knowing which it is. The RAM was then tried on an ABIT IS7 Springdale motherboard with more promising results. It booted in fine at 275MHz FSB (3.3GHz - 12x multiplier) with 2.8v DDR. It was perfectly stable for non-3D tests and very occasionally showed minor Northbridge-related graphical rendering errors in the gaming benchmarks. That suggest we were close the motherboard's limit.
The test, we reckon, is to see how much more favourable it is to have an ultra-high FSB compared to other overclocked FSBs. For example, how would our pseudo 2.4GHz C P4 compare with pseudo 2.6GHz and 2.8GHz CPUs running with lesser memory whilst keeping the overall clock speed as consistent as possible ?. Therefore the following combinations were run:
3301.3MHz - 275.1MHz FSB (12x multiplier, pseudo 2.4GHz C) - DDR550 - 3-4-4-7 SPD timings - Corsair XMS4400 at default speeds
3297.1MHz - 253.6MHz FSB (13x multiplier, pseudo 2.6GHz C) - DDR507.2 - 3-4-4-7 SPD timings - Corsair XMS4400 emulating XMS4000 memory
3308.4MHz - 236.3MHz FSB (14x multiplier, pseudo 2.8GHz C) - DDR472.6 - 3-4-4-7 SPD timings - Corsair XMS4400 emulating XMS3700 memory
That's how CPU-Z sees it.
Vroom, vroom.
An approximation of DDR500 memory and a 2.6GHz 200MHz FSB CPU
And of a 2.8GHz CPU with PC3700-like memory.
