Overclocking

OVERCLOCKING

Description:

Overclocking is the somewhat unknown and uncommon practice of running your CPU (or other parts) past the speed that it is rated at. An example is running a 1.2 GHz CPU at 1.4 GHz or a 200 MHz CPU at 233 MHz. How can this be achieved? The following description isn't exact, but it captures the basic idea. Most CPU companies create their CPUs and then test them at a certain speed. If the CPU fails at a certain speed, then it is sold as a CPU at the next lower speed. The tests are usually very stringent so a CPU may be able to run at the higher speed quite reliably. In fact, the tests are often not used at all. For example, once a company has been producing a certain CPU for awhile, they have gotten the process down well enough that all the CPUs they make will run reliably at the highest speed the CPU is designed for. Thus, just to fill the demand, they will mark some of them as the slower CPUs.
Beware, however, that some vendors may sell CPUs already overclocked. This is why it is very important to buy from a dealer you can trust.
Some video cards are also very overclockable with some companies selling their cards already overclocked (and advertised this way). The Programs like Powerstrip can often be used to easily overclock the cards.
Also, if you're afraid to overclock your CPU, let another company do it for you! Companies like ComputerNerd sell CPUs pretested at overclocked speeds.

What To Consider:

• Do you NEED to overclock? It may not be worth the risk if your computer is running fine as it is. However, if it seems a little too slow and/or you're a speed freak, it may be worth the risk.
• How important is your work? If you're running a very important network server, it may not be worth it to put the extra strain on the computer. Likewise, if your computer does a lot of highly CPU intensive operations, you may also want to not overclock. Obviously the most stable computer is going to be one that is not overclocked. This is not to say that an overclocked computer can not be 100% stable because they CAN. If you just use your computer to play games and would like to have a little faster frame rates, then overlcocking may be worth it.

Potential Side-Effects?

• The first impression people usually have of overclocking is "isn't that dangerous?" For the most part, the answer is no. If all you do to try to overclock your computer is change the CPU's speed, there is very little chance that you will damage your computer and/or the CPU as long as you do not push your computer too hard (i.e. trying to run a 500 MHz CPU at 1 GHz. Damage has happened, but it's a rare thing. Also, if you start increasing voltage settings to allow your CPU to run at a higher speed, there is more of a risk there.
• The best way to prevent damage is to keep your CPU as cool as possible. The only way you can really damage your CPU is if it gets too hot. Adequate cooling is one of the keys to successful overclocking. Using large heatsinks with powerful ball-bearing fans will help to achieve this. How hot is too hot? If you can't keep your finger on the CPU's heatsink comfortably, then it is probably too hot and you should lower the CPU's speed.
• Changing the bus speed is actually more beneficial than changing the CPU's speed. The bus speed is basically the speed at which the CPU communicates with the rest of the computer. When you increase the bus speed, in many cases you will be overclocking all the parts in your AGP, PCI slots, and your RAM as well as the CPU. Usually this is by a small margin and won't hurt these components. Pay attention to them though. If they're getting too hot, you may need to add extra cooling for them (an additional fan in your case). Just like your CPU, if they get too hot, they may be damaged as well.

Difficulty Level:

• Believe it or not, it's actually quite simple. In many cases all you have to do is change a couple of jumpers on the motherboard or change settings in your motherboard's BIOS.

Recommendations:

• Most of today's CPUs are multiplier locked, but you can change the bus speed. As an example, you could run a 1.2 GHz Thunderbird that normally runs at 133 bus (also called 266 because it is "double-pumped) at:
• Multiplier * Bus Speed = CPU speed in MHz
• 9 * 133 = 1,200 MHz = 1.2 GHz = default
• 9 * 140 = 1,260 MHz = 1.26 GHz
• 9 * 145 = 1,305 MHz = 1.3 GHz
• 9 * 150 = 1,350 MHz = 1.35 GHz

Even though that CPU is multiplier locked, you can change the multiplier by connecting the "L1" dots on the CPU itself with a normal pencil (it's just enough to conduct electricity to allow you to change the multipliers). If you do this properly, it is perfectly safe. Here's an article on how to do this.

• 9 * 133 = 1,200 MHz = 1.2 GHz = default
• 9.5 * 133 = 1,264 MHz = 1.264 GHz
• 10 * 133 = 1,333 MHz = 1.333 GHz
• Or change both together, like this:
  10 * 140 = 1,400 MHz = 1.4 GHz
• All you need to do here is use common sense really. For example, you wouldn't want to try to run a 233 MHz CPU at 400 MHz. For one thing, it won't work. For another, that probably would damage your CPU. I would advise starting out low and slowly trying to go higher. If you have a 233 MHz CPU, try running it one step higher, then the next step. Most likely you won't be able to get a CPU like this to run much higher than 300, but that is a possibility.
• Be more concerned with changing the bus speed than the CPU speed as that will provide the greatest amount of speed improvement. For example, running a CPU at 250 (83.3x3) would be better than 262.5 (75x3.5) in most cases because the bus speed of 83 is higher than 75. The default for most CPUs is at 66 MHz bus speed. The newer P2's bus speed is 100 MHz by default. Many computers will not have options on bus speeds, but if you get any of the motherboards I recommend, you will have different bus speed options. The higher bus speed you can run at reliably, the better. Depending on what your other components are though, they may cause your computer to crash or become unstable if they can't handle the higher bus speeds. With bus speeds like 133, you have to have higher quality PC133 or PC2100 DDR SDRAM to be able to achieve this bus speed reliably.

What you'll need:

An open computer case and your motherboard manual is all you'll really need to try it, but more efficient cooling may be useful as well. Of course, your motherboard needs to support the bus speeds you plan to use and the multiplier you plan to use. Your motherboard manual should tell you whether or not it supports certain bus speeds and certain multipliers. If the exact CPU speed using a particular multiplier and bus speed isn't listed, don't worry. If you have the proper multiplier and bus speed in your manual, then you should be okay.

How to calculate your desired speed:

• First consider your default speed. For simplicity, lets say it's 1 GHz. If this is an Athlon processor, it would most likely be running at the 133 MHz bus speed with a multiplier of 7.5 (100x7.5 = 1000 MHz = 1 GHz) or at the 100 MHz bus speed and multiplier of 10 (10x100 = 1000). Let's use the latter instance as an example - 100 MHz bus and 10 multiplier.
• If you wanted to run at around 1.2 GHz you could increase the multiplier to 12 and leave the bus speed alone (100x12 = 1200). *Please note* most of today's CPUs prevent you from changing the multiplier and only allow you to change the bus speed! The step below explains how to do this.
• If you wanted to increase the bus speed and the motherboard supported the higher MHz bus speeds, you could do something like 10x120 for 1200 MHz. Calculate your new speed by multiplying the bus speed by your CPU's multiplier.
• You could also try increasing both the bus speed and multiplier. An example would be increasing the multiplier to 11 and bus speed to 110 MHz for just over 1.2 GHz (11x110 = 1210 MHz).

How to SET this speed:

• In your motherboard manual, find the jumper settings for the particular bus speed and multiplier you want to use. Locate those jumpers on your motherboard and change them to fit the jumper settings in the manual. If it says "closed" for a jumper, then you need to have the little "shunt" placed over the two pins for that jumper which "closes" the connection. If it says "open" you may need to pull off the shunt.
• If your motherboard has a "SoftMenu," then you can change your bus speed and / or multiplier in the computer's BIOS. Usually you will have to press F1 or Del to enter your BIOS while your computer is starting up. Try to locate the CPU speed settings and rotate through the available bus speeds until you find the one you are wanting to try.
• Some motherboards will have both jumpers and a SoftMenu and you can use either one. Others have a combination and you may need to change the bus speed on the motherboard with jumpers, and change the multiplier in the BIOS. That's all there is to it!

If the speed you're trying to run at won't work for some reason, then some of these quick-fix solutions may help...

1. Add additional cooling if your CPU is getting too hot. A fan blowing on the fan that's on the CPU can help. You could also try a bigger/better heatsink and fan combo or a Peliter effect cooler which basically works as a refrigerant for your CPU. Using thermal grease to seal the connection and enhance heat transfer between your CPU and heatsink can also be very helpful.
2. Though it can be dangerous if you go too high, you may want to try increasing the voltage. Not all motherboards support this option though. Do so in small steps if you can and avoid going more than four or five tenths of a volt higher. Make sure your CPU isn't getting too hot as you try this.
3. Sometimes the CPU's cache won't tolerate the higher speeds. Although I wouldn't suggest this to increase performance because it would have the opposite effect, you can disable your CPU's cache in the BIOS just to try to find out if that is what is preventing you from reaching a higher speed. Then change it back later.
4. If you're running a Pentium II and it won't let you run at the 100 MHz bus speed or higher, try to cover up the B21 pin on the CPU. Tom's Hardware Guide has a good description of this. The same applies to the Celeron CPUs.
5. If you have an older hard drive ('97 or earlier), consider lowering the PIO mode in the BIOS as the hard drive may not like the faster bus speed.
6. Adjust memory timings in your BIOS. Take them as low as you can without losing stability in an UNoverclocked situation, then try them in an oveclocked situation. You may have to have slower speeds for your memory to be able to overclock (i.e. run your RAM at CAS 3 when overclocking and CAS 2 when not). CAS 3 would be much slower, but it may allow you to run your CPU faster (and tell you to get faster RAM that will run the higher bus speeds at CAS 2.
7. If you run one of the first Athlon CPUs, look for a "Golden Fingers" card to allow you to overclock the CPU.
8. Here's a long but important note on PCI and AGP cards. If, for example, your system runs at 133 MHz bus speed by default, then increasing your bus speed to 166 overclocks your RAM, PCI cards, and AGP card. At 133, your PCI cards run at 1/4 the bus speed (33 MHz, which is default). At 166, the divisor may remain at 1/4 in which case your PCI cards are overclocked to 41.5 MHz. This may be okay for most PCI devices, but some may have problems. See if your motherboard has a 1/5 divisor for PCI (PCI would then run at the default 33 MHz).
   For AGP (usually more important because AGP more often has problems with higher speeds) the problem is similar. AGP is supposed to run at 66 MHz. At 133 bus, AGP is configured by 1/2 the bus speed (133 * 1/2 = 66). When running at 166 MHz bus speed, your AGP card may overclocked to 83 MHz, which may be too much. If a ratio of 2/5 is supported by your motherboard, then the AGP speed would be at default (166 * 2/5 = 66 MHz).