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rogue_jedi
Supreme [H]ardness
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- Sep 6, 2002
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alrighty... here's the beta version of the OC FAQ. i say beta because i may have missed some stuff and i still have a few things i want to add in. but here you go.
oh, and answer the poll AFTER you read the FAQ. ALL of it.
**Overclocking FAQ**
This is just a compilation of basic hints/tips for overclocking, and a basic overview of what it is and what it involves. PM me if you have an addition or a correction, and I'll mention you if I use it.
How well will X overclock?
YMMV. Not all chips/components overclock the same. Just because Bobby got his Prescott to 5ghz, it doesn't mean yours is guaranteed to do 4ghz. And the like. Each chip is unique in it's overclockability. Some are great, some are duds, most are average (well, duh!). Try it and see. Whether or not you keep it if you get a dud is up to you.
Is this a good overclock?
Are you happy with what you got? If so, then sure (unless it is just a 5% or less overclock - then you need to keep going unless it becomes unstable after that). Otherwise, keep going. If you're at the limit of your chip, then you are at the limit of your chip. Nothing else you can do.
How hot is too hot/How much voltage is too much?
The limits on chips are surprisingly high. For example, the maximum temperature/voltage on a Barton core Athlon XP+ is 85C and 2.0 volts. 2 volts is plenty for most overclocks, and 85C is rather high. A very good reference is this one:
http://users.erols.com/chare/elec.htm
Look there before asking questions about this here. As a general guideline for safe temperatures, temps at full load should be around 55C for a P4 and 55C for Athlons. Lower is better, but don't freak if your temps are high. Check the resource, and see if it is well within specifications (as it likely is). For voltages, 1.65-1.7 is a good limit for a P4 and an Athlon can go up to 1.8 on air/2.0 on water generally speaking. Depending on cooling, more voltage/less voltage may be appropriate.
Do I need better cooling?
Depends on what your current temperatures are and what you're planning to do with your system. If your temperatures are too high, then you probably need better cooling, or at least need to reseat your heatsink and work on cable management. Good cable management can do wonders for case airflow. Also, proper application of thermal paste is very important for temps. Use the guide from the TIM(Thermal Interface Material) manufacturer and follow it as closely as you can. If that doesn't help any or enough, than you probably need better cooling. But see the above section and included link before you start complaining about your temperatures. We don't really want to hear it, unless they are spectacularly bad (or good). Then again, most of those instances can be chalked up to inaccurate temperature sensors on the motherboard. So don't post these questions unless you really can't figure it out and you have tried a few things already.
What are the common methods of cooling?
The most common method is air cooling. This involves putting a fan on top of a heatsink which is then placed on top of the CPU. These can be either very quiet, very loud, or somewhere in between, based on the fan used. They can be fairly effective coolers, but there are more effective cooling solutions. One of these is watercooling, but I'll get into that in a bit.
Air coolers are made by companies such as Zalman, Thermalright, Thermaltake, Swiftech, Alpha, Coolermaster, Vantec, etc. Zalman makes some of the best quiet cooling units and is known for their "flower cooler" design. They have one of the most effective quiet cooling designs in the 7000Cu/AlCu (all copper or aluminum and copper construction) and it is also one of the better performing designs. Thermalright is (quite) arguably the producer of the highest performing heatsinks when used with appropriate fans. Swiftech and Alpha were the performance kings before Thermalright came into the spotlight and are still excellent heatsinks and can be used in more applications than the Thermalright heatsinks because they are generally smaller than the Thermalright heatsinks and so fit on more motherboards. Thermaltake makes an abundance of cheap heatsinks, but they aren't really worth it IMHO. They don't perform on the same level as the other heatsink manufacturers' heatsinks, but they can be used in a pinch or in a budget box. That covers the most popular heatsink manufacturers.
On to watercooling. Watercooling is still mainly a fringe movement, but it is becoming more mainstream all the time. NEC and HP (I believe) make watercooled systems that can be bought retail. Still, most of watercooling is in the enthusiast area. There are several components involved in a watercooling loop, even the most basic one. There is at least one waterblock, usually on the CPU and sometimes the GPU. There is a pump and sometimes a reservoir. There is also a radiator or two.
The waterblocks are generally constructed from copper or (less commonly) aluminum. Even less common, but becoming more so, is waterblocks made of silver. Danger Den makes the S-TDX, and it is possible to procure a silver Cascade block. There are several different kinds of internal designs for waterblocks, but I won't get into those here. Visit the watercooling sub forum to learn more. The pump is responsible for pushing water through the loop. The most common pumps are Eheim pumps (1046, 1048, 1250), Hydor (L20/L30), and the Danner Mag3. Iwaki pumps are also popular among the high-end crowd. The Swiftech MCP600 pump is becoming more popular, as is the Liang D4. Both of those are high-head 12V pumps. A reservoir is helpful because it adds to the volume of the water in the loop and makes filling and bleeding (getting the air bubbles out of the loop) and maintenance easier. However, it takes up a good deal of space in most cases (a small reservoir isn't much good) and it is just one more thing that could leak. The radiator can either be a retail one, such as Swiftech's radiators, or made from a heatercore from a car. The heatercores generally offer superior performance as well as a lower price tag, but are also harder to assemble, as they usually don't come in a form that can be adopted to watercooling quickly. Again, look at the watercooling sub forum for more info. The tubing is also a factor in performance. Generally, 1/2" ID is considered to be the best for high performance. However, 3/8" and even 1/4" ID setups are becoming more common, and their performance is also getting closer to that of a 1/2" ID loop. That's about it for watercooling in this section.
What are some of the less common cooling types?
Phase change, chilled water, peltier, and submersion setups are less common, but higher performance, cooling alternatives to those listed above. Ask in the extreme cooling sub forum about any of these methods. Read up on any of these before you use them. Peltier cooling and chilled water loops are both based on watercooling, in that they are based on a modified watercooling loop. Peltier is the most common of these types. A peltier is a device that, when current is applied, gets hot on one side and cold on the other. This can be used between a CPU and a waterblock or a GPU and a waterblock. Less common is peltier cooled northbridges, but this isn't really necessary. Ever. A chilled water loop uses either a peltier or phase change to cool off the water in the loop, usually replacing the radiator in the loop cooling the CPU/GPU. Using a peltier to do this is not very effective, because it often requires another watercooling loop to cool it off. The peltier is generally sandwiched between either a heatsink and a waterblock or a waterblock and another waterblock. The phase change method involves placing the cooling head or cooling component from an A/C unit or the like in a reservoir. Antifreeze is usually added to the water in about a 50/50 ratio in chilled water setups, because freezing isn't good. The tubing has to be insulated as do the blocks if sub ambient temperatures are ever reached in case of condensation. Phase change involves a compressor and a cooling head attached to the CPU or sometimes the GPU. I won't go into much depth about it here. Read up on it at overclockers.com or the extreme cooling sub forum.
Other less common methods involve dry ice, liquid nitrogen, watercooling the PSU and hard drives, and other things like that. Using the case as a heatsink has also been considered and done as well.
I just thought up a cool idea for cooling, is it original?
Is it listed up above? If so, then no. Also, the search function is a wonderful thing now that it works.
My cool idea has been listed already, should I post it?
Only if you are in the process of doing it. Then we want - no, demand - pictures. Hypothetical discussions are okay, but make sure it is something useful. Don't let me discourage you though, just don't take it too hard if no one cares.
What about prebuilt watercooling units?
The Koolance one and the Corsair one are the only ones really worth considering. The little Globalwin one is alright, but no better than any half-decent air cooling. The rest are no better. Avoid them. The newest Thermaltake one may be alright, but see the above warning about Thermaltake products. New kits may be decent (The kingwin one seems to be so) but read multiple reviews and at least one that tests it on the platform you will be using before buying anything.
How do I overclock?
This is a rather complex question, but the basics are pretty easy. The simplest method is to just raise the FSB. This will work on almost any platform. However, Via chipsets (KT266/333/400(a)/600 and possibly the KT880 - not clear on that one yet as well as the K8T800) do not have a PCI/AGP lock, so you have to be careful about raising the FSB, as running the PCI bus out of spec (33mhz) can corrupt hard drive data, prevent peripherals from functioning correctly (especially ATI AGP video cards), and generally cause instability. This will be revisited later. The nForce2 chipset for AMD's XP chip, the nForce3 250 (the 150 is unlocked on most boards, but some motherboards have either dividers or rudimentary locks to allow higher FSB, but I'm not an expert on these - ask around), the Via K8T800 Pro, and the Intel 865/875 chipsets all possess locked PCI frequencies. This makes adjusting the FSB far easier, as it removes certain limiting factors, such as frequency-sensitive peripherals (most of them). However, limits still exist. Besides the limit imposed by the chip itself, the RAM and the chipset, as well as the motherboard itself, can limit the FSB that can be attained. That is where multiplier adjustment comes in.
On certain Athlon XP chips, the multiplier is adjustable. These chips are referred to as 'unlocked.' The Athlon 64 series (I believe) allows multiplier adjustment to lower multipliers only aside from the fully unlocked FX series. The Pentium 4 is locked unless you have acquired an engineering sample through some stroke of luck or ebay. However, almost all motherboards allow multiplier adjustment as long as the chip supports it. For the Athlon XP boards that don't, a pinmodding guide to raise/lower the multiplier is available in the 'workshop' section of ocinside.de/index_e.html. The site explains how to perform the modification and also has several other useful tools.
Once the system becomes unstable because of the CPU limitations, there are two options. You can either back down a little to where it is stable, or you can raise the CPU voltage (and possibly the RAM and AGP voltages) to where it becomes stable, or even raise it higher and keep pushing the overclock. You can also try 'loosening' the memory timings (raising the numbers) until it becomes stable if raising the CPU voltage doesn't help or raising the memory voltage. If none of these help, your motherboard may have a provision for raising the chipset voltage, which can help if your chipset is adequately cooled. If nothing helps, you may need better cooling on the CPU or other components (cooling the MOSFETS - the little chips next to the CPU socket which regulate power - can help and is rather common) If that still doesn't help, or the gain is only marginal, you are at the limit of your chip or your motherboard. If lowering the voltage doesn't hurt stability than it is most likely your motherboard. Voltmodding the chipset is a possibility, but is a bit advanced and requires better cooling than the stock. Also, cooling the southbridge as well as the northbridge may help, or may improve stability. I know that on my motherboard, the integrated sound starts to crackle if I run WinAMP/XMMS and UT2004 (this happens in both Windows and Linux) no matter the FSB if i don't have a heatsink on the southbridge. So it isn't a bad idea, but may not be necessary. It also generally voids your warranty (more than overclocking does - overclocking can usually be undone without a trace)
That covers basic overclocking. More advanced overclocking usually involves adding heatsinks to everything, voltmodding the motherboard and possibly power supply, adding more/better fans and/or watercooling and/or phase change/cascade cooling. Google can help you learn about the more extreme side of overclocking.
What do I do if my computer won't post? (Display the BIOS screen when it is turned on)
This varies based on the motherboard you have. The "fail-safe" solution (unless you killed something) is to reset the CMOS, usually by moving a jumper for a set amount of time. Check your motherboard manual for the specifics. Most recent enthusiast level boards have an option to post at reduced frequencies if the overclock is pushed too high but leave the BIOS settings intact, so you can go in and lower the clock speed to where it is stable. On some motherboards, this is done by holding the Insert key when you turn on the computer (usually has to be a PS/2 keyboard). The DFI LanParty PRO875 is one such board. Others automatically reduce the frequency if the computer didn't post on the previous attempt. The A7N8X usually does this. Sometimes a computer will not cold boot (post when the power button is pressed) but will work if it is left on for a while, then reset. On other occasions the computer will cold boot fine, but will fail to warm boot (reboot). Those are both indications of instability, but if you are happy with the stability and able to deal with the issues than it usually won't cause any huge problems.
What limits my overclock?
Generally, the RAM and CPU are the only significant limiting factors, especially in AMD systems because of the problems inherent in running the memory asynchronously (see the FSB section down below) The RAM has to run at the same speed as the FSB or at a fraction of it. Complex fractions are allowed, meaning the memory can be run at a higher rate than the FSB, not just a lower one. With the option to run looser timings/more voltage through memory, though, it is becoming less and less the limiting factor, especially since newer platforms (P4 and A64) suffer less of a performance hit from running async. (again, see below) The CPU has become the main limiting factor. The only way to deal with a CPU that doesn't want to run any faster is to pump more voltage through it, though exceeding the maximum core voltage shortens the life of the chip (though overclocking does this as well) but sufficient cooling stems this problem. Another problem with running too high of a core voltage manifested itself on the P4 platform in the form of SNDS, or Sudden Northwood Death Syndrome, wherein running any voltage over something like 1.7 (not sure of the exact number, no one is) would result in the quick and untimely death of the processor, even with phase change cooling. However, the newer 'C' core chips, the EE chips, and the Prescott chips have not had this problem, at least not to nearly the same extent. The cooling can also prevent a good overclock, as having temps that are too high can lead to instability. But if your system is stable, then the temps usually are not too high.
What are the dangers of overclocking?
There are several dangers attached to overclocking, and they should definitely not be overlooked. Running any component out of spec will shorten its lifespan; though newer chips are able to deal with this far better than older ones, so this is less of a problem than it used to be, especially if you upgrade every 6 months or every year. For long term stability, IE computers that are going to be running for more than 2 years or so with a load most of the time, overclocking is not a good idea. Also, there is the possibility that overclocking will corrupt data, so if you don't do backups of any data you care about, overclocking is not really for you (and you should really start doing backups anyway) unless you can easily replicate the data and it will not cause any problems. But take possible data loss into account BEFORE you start overclocking. You will thank yourself for doing this if anything goes wrong. Overclocking (especially large overclocks at a high voltage) is not recommended if you only have one computer and you need it for anything important, as the possibility of component failure is quite real (I have lost a few components to overclocking, but not as many as some have lost) so that needs to be taken into account as well. On a lighter note, addiction and "Empty Wallet Syndrome" are also very real risks to overclocking
. Be careful of those.
Now that I've overclocked a lot, what should I do?
Run some benchmarks if you want to. Run Prime95 (Or your stress test of choice - it is up to you) for a sufficient time period (Usually 24 hours straight is considered a stable system)
/Begin shameless F@H plug
Then install Folding@Home if you haven't already.
/End shameless F@H plug
That covers the basic aspects of overclocking. The questions from this point on are the more technically involved sections.
oh, and answer the poll AFTER you read the FAQ. ALL of it.
**Overclocking FAQ**
This is just a compilation of basic hints/tips for overclocking, and a basic overview of what it is and what it involves. PM me if you have an addition or a correction, and I'll mention you if I use it.
How well will X overclock?
YMMV. Not all chips/components overclock the same. Just because Bobby got his Prescott to 5ghz, it doesn't mean yours is guaranteed to do 4ghz. And the like. Each chip is unique in it's overclockability. Some are great, some are duds, most are average (well, duh!). Try it and see. Whether or not you keep it if you get a dud is up to you.
Is this a good overclock?
Are you happy with what you got? If so, then sure (unless it is just a 5% or less overclock - then you need to keep going unless it becomes unstable after that). Otherwise, keep going. If you're at the limit of your chip, then you are at the limit of your chip. Nothing else you can do.
How hot is too hot/How much voltage is too much?
The limits on chips are surprisingly high. For example, the maximum temperature/voltage on a Barton core Athlon XP+ is 85C and 2.0 volts. 2 volts is plenty for most overclocks, and 85C is rather high. A very good reference is this one:
http://users.erols.com/chare/elec.htm
Look there before asking questions about this here. As a general guideline for safe temperatures, temps at full load should be around 55C for a P4 and 55C for Athlons. Lower is better, but don't freak if your temps are high. Check the resource, and see if it is well within specifications (as it likely is). For voltages, 1.65-1.7 is a good limit for a P4 and an Athlon can go up to 1.8 on air/2.0 on water generally speaking. Depending on cooling, more voltage/less voltage may be appropriate.
Do I need better cooling?
Depends on what your current temperatures are and what you're planning to do with your system. If your temperatures are too high, then you probably need better cooling, or at least need to reseat your heatsink and work on cable management. Good cable management can do wonders for case airflow. Also, proper application of thermal paste is very important for temps. Use the guide from the TIM(Thermal Interface Material) manufacturer and follow it as closely as you can. If that doesn't help any or enough, than you probably need better cooling. But see the above section and included link before you start complaining about your temperatures. We don't really want to hear it, unless they are spectacularly bad (or good). Then again, most of those instances can be chalked up to inaccurate temperature sensors on the motherboard. So don't post these questions unless you really can't figure it out and you have tried a few things already.
What are the common methods of cooling?
The most common method is air cooling. This involves putting a fan on top of a heatsink which is then placed on top of the CPU. These can be either very quiet, very loud, or somewhere in between, based on the fan used. They can be fairly effective coolers, but there are more effective cooling solutions. One of these is watercooling, but I'll get into that in a bit.
Air coolers are made by companies such as Zalman, Thermalright, Thermaltake, Swiftech, Alpha, Coolermaster, Vantec, etc. Zalman makes some of the best quiet cooling units and is known for their "flower cooler" design. They have one of the most effective quiet cooling designs in the 7000Cu/AlCu (all copper or aluminum and copper construction) and it is also one of the better performing designs. Thermalright is (quite) arguably the producer of the highest performing heatsinks when used with appropriate fans. Swiftech and Alpha were the performance kings before Thermalright came into the spotlight and are still excellent heatsinks and can be used in more applications than the Thermalright heatsinks because they are generally smaller than the Thermalright heatsinks and so fit on more motherboards. Thermaltake makes an abundance of cheap heatsinks, but they aren't really worth it IMHO. They don't perform on the same level as the other heatsink manufacturers' heatsinks, but they can be used in a pinch or in a budget box. That covers the most popular heatsink manufacturers.
On to watercooling. Watercooling is still mainly a fringe movement, but it is becoming more mainstream all the time. NEC and HP (I believe) make watercooled systems that can be bought retail. Still, most of watercooling is in the enthusiast area. There are several components involved in a watercooling loop, even the most basic one. There is at least one waterblock, usually on the CPU and sometimes the GPU. There is a pump and sometimes a reservoir. There is also a radiator or two.
The waterblocks are generally constructed from copper or (less commonly) aluminum. Even less common, but becoming more so, is waterblocks made of silver. Danger Den makes the S-TDX, and it is possible to procure a silver Cascade block. There are several different kinds of internal designs for waterblocks, but I won't get into those here. Visit the watercooling sub forum to learn more. The pump is responsible for pushing water through the loop. The most common pumps are Eheim pumps (1046, 1048, 1250), Hydor (L20/L30), and the Danner Mag3. Iwaki pumps are also popular among the high-end crowd. The Swiftech MCP600 pump is becoming more popular, as is the Liang D4. Both of those are high-head 12V pumps. A reservoir is helpful because it adds to the volume of the water in the loop and makes filling and bleeding (getting the air bubbles out of the loop) and maintenance easier. However, it takes up a good deal of space in most cases (a small reservoir isn't much good) and it is just one more thing that could leak. The radiator can either be a retail one, such as Swiftech's radiators, or made from a heatercore from a car. The heatercores generally offer superior performance as well as a lower price tag, but are also harder to assemble, as they usually don't come in a form that can be adopted to watercooling quickly. Again, look at the watercooling sub forum for more info. The tubing is also a factor in performance. Generally, 1/2" ID is considered to be the best for high performance. However, 3/8" and even 1/4" ID setups are becoming more common, and their performance is also getting closer to that of a 1/2" ID loop. That's about it for watercooling in this section.
What are some of the less common cooling types?
Phase change, chilled water, peltier, and submersion setups are less common, but higher performance, cooling alternatives to those listed above. Ask in the extreme cooling sub forum about any of these methods. Read up on any of these before you use them. Peltier cooling and chilled water loops are both based on watercooling, in that they are based on a modified watercooling loop. Peltier is the most common of these types. A peltier is a device that, when current is applied, gets hot on one side and cold on the other. This can be used between a CPU and a waterblock or a GPU and a waterblock. Less common is peltier cooled northbridges, but this isn't really necessary. Ever. A chilled water loop uses either a peltier or phase change to cool off the water in the loop, usually replacing the radiator in the loop cooling the CPU/GPU. Using a peltier to do this is not very effective, because it often requires another watercooling loop to cool it off. The peltier is generally sandwiched between either a heatsink and a waterblock or a waterblock and another waterblock. The phase change method involves placing the cooling head or cooling component from an A/C unit or the like in a reservoir. Antifreeze is usually added to the water in about a 50/50 ratio in chilled water setups, because freezing isn't good. The tubing has to be insulated as do the blocks if sub ambient temperatures are ever reached in case of condensation. Phase change involves a compressor and a cooling head attached to the CPU or sometimes the GPU. I won't go into much depth about it here. Read up on it at overclockers.com or the extreme cooling sub forum.
Other less common methods involve dry ice, liquid nitrogen, watercooling the PSU and hard drives, and other things like that. Using the case as a heatsink has also been considered and done as well.
I just thought up a cool idea for cooling, is it original?
Is it listed up above? If so, then no. Also, the search function is a wonderful thing now that it works.
My cool idea has been listed already, should I post it?
Only if you are in the process of doing it. Then we want - no, demand - pictures. Hypothetical discussions are okay, but make sure it is something useful. Don't let me discourage you though, just don't take it too hard if no one cares.
What about prebuilt watercooling units?
The Koolance one and the Corsair one are the only ones really worth considering. The little Globalwin one is alright, but no better than any half-decent air cooling. The rest are no better. Avoid them. The newest Thermaltake one may be alright, but see the above warning about Thermaltake products. New kits may be decent (The kingwin one seems to be so) but read multiple reviews and at least one that tests it on the platform you will be using before buying anything.
How do I overclock?
This is a rather complex question, but the basics are pretty easy. The simplest method is to just raise the FSB. This will work on almost any platform. However, Via chipsets (KT266/333/400(a)/600 and possibly the KT880 - not clear on that one yet as well as the K8T800) do not have a PCI/AGP lock, so you have to be careful about raising the FSB, as running the PCI bus out of spec (33mhz) can corrupt hard drive data, prevent peripherals from functioning correctly (especially ATI AGP video cards), and generally cause instability. This will be revisited later. The nForce2 chipset for AMD's XP chip, the nForce3 250 (the 150 is unlocked on most boards, but some motherboards have either dividers or rudimentary locks to allow higher FSB, but I'm not an expert on these - ask around), the Via K8T800 Pro, and the Intel 865/875 chipsets all possess locked PCI frequencies. This makes adjusting the FSB far easier, as it removes certain limiting factors, such as frequency-sensitive peripherals (most of them). However, limits still exist. Besides the limit imposed by the chip itself, the RAM and the chipset, as well as the motherboard itself, can limit the FSB that can be attained. That is where multiplier adjustment comes in.
On certain Athlon XP chips, the multiplier is adjustable. These chips are referred to as 'unlocked.' The Athlon 64 series (I believe) allows multiplier adjustment to lower multipliers only aside from the fully unlocked FX series. The Pentium 4 is locked unless you have acquired an engineering sample through some stroke of luck or ebay. However, almost all motherboards allow multiplier adjustment as long as the chip supports it. For the Athlon XP boards that don't, a pinmodding guide to raise/lower the multiplier is available in the 'workshop' section of ocinside.de/index_e.html. The site explains how to perform the modification and also has several other useful tools.
Once the system becomes unstable because of the CPU limitations, there are two options. You can either back down a little to where it is stable, or you can raise the CPU voltage (and possibly the RAM and AGP voltages) to where it becomes stable, or even raise it higher and keep pushing the overclock. You can also try 'loosening' the memory timings (raising the numbers) until it becomes stable if raising the CPU voltage doesn't help or raising the memory voltage. If none of these help, your motherboard may have a provision for raising the chipset voltage, which can help if your chipset is adequately cooled. If nothing helps, you may need better cooling on the CPU or other components (cooling the MOSFETS - the little chips next to the CPU socket which regulate power - can help and is rather common) If that still doesn't help, or the gain is only marginal, you are at the limit of your chip or your motherboard. If lowering the voltage doesn't hurt stability than it is most likely your motherboard. Voltmodding the chipset is a possibility, but is a bit advanced and requires better cooling than the stock. Also, cooling the southbridge as well as the northbridge may help, or may improve stability. I know that on my motherboard, the integrated sound starts to crackle if I run WinAMP/XMMS and UT2004 (this happens in both Windows and Linux) no matter the FSB if i don't have a heatsink on the southbridge. So it isn't a bad idea, but may not be necessary. It also generally voids your warranty (more than overclocking does - overclocking can usually be undone without a trace)
That covers basic overclocking. More advanced overclocking usually involves adding heatsinks to everything, voltmodding the motherboard and possibly power supply, adding more/better fans and/or watercooling and/or phase change/cascade cooling. Google can help you learn about the more extreme side of overclocking.
What do I do if my computer won't post? (Display the BIOS screen when it is turned on)
This varies based on the motherboard you have. The "fail-safe" solution (unless you killed something) is to reset the CMOS, usually by moving a jumper for a set amount of time. Check your motherboard manual for the specifics. Most recent enthusiast level boards have an option to post at reduced frequencies if the overclock is pushed too high but leave the BIOS settings intact, so you can go in and lower the clock speed to where it is stable. On some motherboards, this is done by holding the Insert key when you turn on the computer (usually has to be a PS/2 keyboard). The DFI LanParty PRO875 is one such board. Others automatically reduce the frequency if the computer didn't post on the previous attempt. The A7N8X usually does this. Sometimes a computer will not cold boot (post when the power button is pressed) but will work if it is left on for a while, then reset. On other occasions the computer will cold boot fine, but will fail to warm boot (reboot). Those are both indications of instability, but if you are happy with the stability and able to deal with the issues than it usually won't cause any huge problems.
What limits my overclock?
Generally, the RAM and CPU are the only significant limiting factors, especially in AMD systems because of the problems inherent in running the memory asynchronously (see the FSB section down below) The RAM has to run at the same speed as the FSB or at a fraction of it. Complex fractions are allowed, meaning the memory can be run at a higher rate than the FSB, not just a lower one. With the option to run looser timings/more voltage through memory, though, it is becoming less and less the limiting factor, especially since newer platforms (P4 and A64) suffer less of a performance hit from running async. (again, see below) The CPU has become the main limiting factor. The only way to deal with a CPU that doesn't want to run any faster is to pump more voltage through it, though exceeding the maximum core voltage shortens the life of the chip (though overclocking does this as well) but sufficient cooling stems this problem. Another problem with running too high of a core voltage manifested itself on the P4 platform in the form of SNDS, or Sudden Northwood Death Syndrome, wherein running any voltage over something like 1.7 (not sure of the exact number, no one is) would result in the quick and untimely death of the processor, even with phase change cooling. However, the newer 'C' core chips, the EE chips, and the Prescott chips have not had this problem, at least not to nearly the same extent. The cooling can also prevent a good overclock, as having temps that are too high can lead to instability. But if your system is stable, then the temps usually are not too high.
What are the dangers of overclocking?
There are several dangers attached to overclocking, and they should definitely not be overlooked. Running any component out of spec will shorten its lifespan; though newer chips are able to deal with this far better than older ones, so this is less of a problem than it used to be, especially if you upgrade every 6 months or every year. For long term stability, IE computers that are going to be running for more than 2 years or so with a load most of the time, overclocking is not a good idea. Also, there is the possibility that overclocking will corrupt data, so if you don't do backups of any data you care about, overclocking is not really for you (and you should really start doing backups anyway) unless you can easily replicate the data and it will not cause any problems. But take possible data loss into account BEFORE you start overclocking. You will thank yourself for doing this if anything goes wrong. Overclocking (especially large overclocks at a high voltage) is not recommended if you only have one computer and you need it for anything important, as the possibility of component failure is quite real (I have lost a few components to overclocking, but not as many as some have lost) so that needs to be taken into account as well. On a lighter note, addiction and "Empty Wallet Syndrome" are also very real risks to overclocking
. Be careful of those.Now that I've overclocked a lot, what should I do?
Run some benchmarks if you want to. Run Prime95 (Or your stress test of choice - it is up to you) for a sufficient time period (Usually 24 hours straight is considered a stable system)
/Begin shameless F@H plug
Then install Folding@Home if you haven't already.
/End shameless F@H plug
That covers the basic aspects of overclocking. The questions from this point on are the more technically involved sections.
