Requirements For Bus Speed Overclocking
Basically you only have to ensure that all components work properly at the higher clock speed. If you overclock a system by rising the processor core speed (by changing the multiplier), you can be sure that the processor will be responsible for all types of troubles. Of course this is quite different with bus speed overclocking: All related clocks and components will run faster as well: Chipset north bridge including memory controller, the main memory, PCI and AGP and the CPU Front Side Bus. Even if only one component fails you will have to spend some time to find out which one.
- Good memory
Keep some reserves. With 66 MHz systems it's best to use PC100 memory or at least brand 10ns types. They should usually bear 75 MHz without any complaint. For 112 MHz, take at least 8 ns PC100 SDRAM. 7 ns are of course better, but those speed numbers are not as important as having memory from a reliable manufacturer like Micron, SEC, Toshiba, Infineon, Viking or others. The best is of course to use PC133 memory, but I don't think that many of you will buy new memory only for overclocking. I wouldn't do it either.
For overclocking from 133 to 150 MHz, we used good quality SDRAM from
Crucial/Micron, which easily withstands most hardcore memory timings.
- Quality components
Each component you want to overclock has to work reliably at the higher clock speed. Critical components are network cards or SCSI adapters as well as some graphic cards. Make sure that your components run properly at your bus speed setting. Don't expect cheap products to run properly. It is likely they won't cause problems, but of course nobody can guarantee this to you. The limit for timing-sensitive PCI cards is usually 36-38 MHz (or about 75 MHz for AGP graphic cards), this means that you should do intensive testings with your new bus speed:
Does the SCSI card work properly: Can I burn CDs without errors? Does the SCSI scanner work? Are all drives working well?
A graphic card may boot up and show the Windows desktop, but what about 3D graphics? Does everything run as expected? Is the picture corrupted?
The 150 MHz Project
Of course I used our "standard benchmarks" for the 150 MHz speed tests: SYSmark 2000 using Windows 98 SE and Windows NT 4.0 SP6a, Quake III Arena and Expendable. The SYSmark consists of two parts: Internet Content Creation and Office Productivity. This time I will give you those single results as well, since it makes it easier to show which applications will benefit from higher bus speeds.
Internet Content Creation uses Bryce 4, Elastic Reality 3.1, Photoshop 5.5, Premiere 5.1 and the Windows Media Encoder 4.0. To get the Office Productivity result, BAPCo makes use of Corel Draw 9, Excel 2000, Naturally Speaking 4.0, Netscape Communicator 4.61, Paradox 9, Powerpoint 2000 and Word 2000.
We were using a Pentium IIIEB 667 for these tests. Luckily this engineering sample allows this multiplier to be changed. We did benchmarks at 100 MHz FSB, clocking the CPU at 650, 700, 750 and 800 MHz. At 133 MHz FSB, we took 667, 733 and 800 MHz. I would have loved to give you the results at 825/150 MHz, but the CPU didn't allow the SYSmark to complete. Therefore we can merely provide the game benchmarks, although I think they are quite impressive.