|You're not going to be able to overclock that machine thru the BIOS, but the motherboard may have jumpers for controlling bus speed and CPU voltage. Many older machines--even OEM rigs--had such jumpers.|
Do you know what chipset your motherboard is based on? How about memory speed? Here are some general guidelines.
If you have a:
440LX or 440EX chipset: 75MHz would be a safe maximum bus speed. This would take your CPU to 488MHz (75x6.5).
440BX, 440ZX, i810, or i815 chipset with PC-66 memory: same max overclock as above
440BX, 440ZX, i810, or i815 chipset with PC-100 memory: You could try taking the CPU bus to 100MHz (make sure to limit the PCI bus to 33MHz by picking the 100/33 (or 100/66MHz AGP) setting). This would give you a CPU speed of 650MHz. However, 650MHz would be pushing the limits of a 250nm Celeron. You may need to increase the CPU voltage to keep things running smoothly. If your board has Vcore jumpers, set the CPU voltage at around 2.1-2.2v, if Windows hangs.
Avoid the 83MHz bus setting--you don't want your PCI bus running at 41.5MHz.
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