What is overclocking?

Overclocking is the method used by many people to improve the performance of their systems. It's the cheapest way to improve the performance as no new perchase of components is required. The performance gain is achieved solely by forcing the chip to operate at a faster clock speed.

In my experience, there is no harm in overclocking providing that sufficient care is taken. An overclocked chip usually generates more heat than a chip running at its native(qualified) speed. System crashes could occur if the heat is not managed properly. I would say that a heat sink with a colling fan is a requirement if you want to overclock your chip.

I've heard some rumour about data loss from overclocking. Personally, I haven't had this experience but anything could happen when you force a processor to run at a speed it's not supposed to be running at. If you don't want to take the risk, don't do it.

How to overclock.

You can overclock Pentiums by changing either the external clock or the Int/Ext clock ratio or both the external clock and Int/Ext clock ratio. By making these changes, you alter the clock frequency sent to the CPU and force the CPU to operate at a higher speed. To make these changes, you should know the default setting for your chip. If you don't know the default setting for your chip, please, look at the table below.

Theoretically, you should be able to set the CPU's internal clock to any speed as they take the clock generated by motherboards. Unfortunately, it doesn't work that way in the real world. Generally, I would recommend one step overclocking.

Chips like P90, P120 and P150 run on 60MHz external clock. If you use one of these chips, you can change the external clock to increase the speed of the chip. The highest clock speed of the current generation of Pentium motherboards is at 66MHz. You can adjust the external clock by changing jumper setting on your motherboard. The information on how to set these jumpers and where they are located are usually in the manual. If you don't have the manual, look at your motherboard. Some manufacturers also put it there in print.

If you have a 75MHz chip, you can clock it up to 90MHz or 100MHz as you can change the external clock setting from 50MHz(default setting for 75MHz) to 60MHz to make the chip run at 90MHz or 66MHz to make it run at 100MHz. Under this type of overclocking, it is the only chip you have more than one choice.

I'm using GA-586ATE/P and GA-586HX. If you use these models, the jumpers are JP4 and JP5 on the ATE/P and SW1,2,3,4 on the HX.

This type of overclocking is for people using P100 and P133. These chips use 66MHz external clock. As a result, you cannot use the first method of overclocking to increase the speed of the chips as the external clock is already at its highest(66MHz) so adjusting the internal/external clock ratio is your only option. Like the previous method, there are jumpers on the motherboard which are used for adjusting the clock ratio. The location and how to set these jumpers are usually in the manual. The other place where you may find this information is the motherboard itself. Some manufacturers print this information on their boards as well.

If you use the GA-586ATE/P, the jumper is JP6. If you use the new GA-586HX, the setting is done on SW1, 2, 3 and 4.

After changing the setting, the chips will be reported as P133 instead of P100 and P166 instead of P133. If you think the internal clock is far too high, you can reset the external clock to 60MHz in order to slow down the internal clock. In this case, the chips will be reported as P120 and P150 instead.

This method can also be used to overclock the P166. I've never tried the 180MHz setting but have tried the 200MHz setting.