Overclocking Info FAQ Guide   What is Overclocking? Quite simply: Overclocking is running your computer at a faster clock speed than the manufacturer's specifications. But, why do we overclock our computers? Well, this brings us to the philosophy of overclocking. Different people have different reasons for overclocking. For some, it's to save money by maximizing their computer components. Gamers overclock in order to increase frame rates in their favorite 3D game. For others, it's a challenging hobby, not unlike hotrodding a car. A few folks do it for bragging rights and to have a faster computer than their buddies. Overclocking Disclaimers No two computers will overclock the same, even if they're identical. Just because "Joe Overclocker" is running his Celeron chip at two million MHz, does not mean that your CPU will do the same. Often, it's several different factors (including luck) that allow some systems to overclock more than others. There are absolutely no guarantees in overclocking. Despite your computer geek skills and knowledge, you are dealing with random chance to a degree. Is there a risk of damaging components when overclocking? Why yes, of course. However, if you use common sense and follow the basic guidelines laid out in this article, then the risks are extremely low to nearly non-existent. Too much heat and too much voltage are the most frequent methods of frying components. Overclock at your own risk! Don't blame me if you toast a component! Also, most warranties are void if they find out you were overclocking. Basic Overclocking Components Computer Case: There are two schools of thought here: One is to take a generic cheap-o case, cut and hack holes into it, and then mount a host of fans into the newly modded case. Most cases have one exhaust fan at the power supply and one intake fan in the front lower area. You probably need at least two more case fans, another intake and exhaust. Plan ahead when installing extra fans. For example, put the intakes all in the front and the exhaust fans in the back, so they're not fighting each other. For those that aren't handy with power tools or just plain lack the time to modify a case, then spend the extra money and get a good case with all the cooling stuff already built into it. Consider getting a case big enough where nothing overhangs the motherboard. Removable mobo tray and side panels are great features. Power Supply: You need a good quality power supply for overclocking, because bumping up the CPU core voltage, using multiple fans, water cooling pumps, and other stuff like that requires lots of extra wattage. Most cases already have a power supply. If you tried to save money by getting a cheap generic case, then you got a cheap generic 235 watt power supply too. In my opinion, a 300 watt power supply is minimum nowadays, and if you're ever planning on running a power hungry AMD processor then think about buying a 400w unit. Motherboard: It does not pay to be cheap here. If you can't afford a good motherboard, then save some bucks, mow some lawns for extra cash, beg your spouse, borrow from Mom and Dad, or do whatever you have to do to get enough money to buy a high quality motherboard. DO NOT SKIMP! This is the heart of your machine. You want a mobo with lots of FSB and voltage adjustments that can be easily changed in the BIOS. CPU: Do a whole bunch of research, ask lots of questions, and then do a fair amount of shopping around before investing in a processor. Look at the Overclockers.com CPU database to see which chips have been successfully overclocked. Personally, the best Intel chip for your overclocking buck right now is the Celeron 600 or the P-III 700. I don't have much AMD experience, but the Duron or the Athlon are very definitely worth considering too. Choose which motherboard you want first and then find a CPU to match your system. COOLING!: This is extremely important when you're overclocking. I can't stress cooling enough. Heat is the enemy! Do not try to raise the core voltage until you have good cooling. Forget the factory retail CPU heatsink and fan. Forget the Golden ORB, it's overclocking days are over. For the price, it's real hard to beat GlobalWin or Alpha coolers right now. When installing your CPU cooler, use a good quality thermal paste. Do not attempt to use that crappy thermal tape that comes with most coolers. Arctic Silver thermal paste is probably the best. However, for the budget minded, Radio Shack thermal paste is a good substitute. Other things you can do to improve cooling are as simple and cheap as rerouting power wires and securing them out of the way. Additionally, round your flat data cables by wrapping them with electrical or duct tape and moving them out of the way. This trick vastly improves air circulation through the case interior and cost very little to do. RAM Memory: This is another place that you should not get cheap generic parts. Buy the best and the most you can afford. The minimum should be PC-133, preferably one 256 meg stick rather than two 128 meg modules. Crucial, Kingmax, and Corsair are all good brands. Lots of PC-150 memory available right now too. Choose CAS-2 rated RAM because it's faster and more overclockable than the normal CAS-3 memory. Video Card: Fortunately, most of the newer AGP 3D video cards seem quite tolerant to overclocking. I prefer the GeForce 2 video cards, especially the Hercules brand, but there are lots of other good GF2 cards on the market. Many folks swear by the Radeon cards too, but I don't have any personal experience with them. The 3dfx Voodoo cards are real decent graphics cards, but they went out of business, so future support will be non-existent; I'd probably avoid the Voodoo cards if I were you. There is a new budget video card out called Kryo II that is looking promising, but we don't know how well they'll overclock yet. Hard drives: High quality hard drives are worth there weight in gold to the overclocker. Extreme overclocking can cause data corruption and, in rare occasions, scramble your hard drive. Usually the drive is not permanently damaged and can be reformatted, but it's a huge hassle if you don't have your data backed up. Plan on spending a little extra and get a fast ATA100 hard drive that spins at 7,200 RPM - if your motherboard supports it. Maxtor has a great warranty and I've had good luck with them, but right now the overclocking king is the IBM hard drive in either the 20 gig or 30 gig flavor. Other Components: Overclocking usually causes the PCI bus to run out of spec (faster than normal), therefore, you'll need to buy, beg, or borrow good components that will run OK when overclocked. CD-ROM drives, sound cards, modems, and other miscellaneous components should all be high quality and selected because they can handle being overclocked. The old style ISA cards should be completely avoided if possible, they will just hurt performance. In fact, choose a motherboard without ISA slots for best results. Basic Overclocking Procedures If you have built a computer following these basics, then the actual overclocking part will be quite easy. Make sure you have good cooling and watch your CPU load temps like a hawk. The better motherboards will have temperature monitoring capabilities. After each step of the overclocking process, thoroughly test your computer system for stability. I use the following programs: SiSoft Sandra, Prime95, 3DMark2000, and the Unreal game demo loop. Monitoring temps and testing for stability is critical during all phases of overclocking. First, make sure the computer runs OK at the default settings. Your objective is to find the highest, stable CPU speed. So for: INTEL CPUs: Increase the front side bus (FSB) speed a little at a time, then test for stability. Intel's CPU multiplier can not be changed, so increasing bus speed is the only way to overclock. Repeat until it becomes unstable. AMD CPUs: Increase the front side bus (FSB) speed a little at a time. AMD's CPUs can be altered so that changing the CPU Multiplier is possible (see Beginner's Guides for details). Note that you may have to decrease the multiplier if the CPU becomes unstable. Test for stability. Repeat until it becomes unstable. For best performance, you want to find the highest FSB and CPU speed that will run your system without any problems. If the computer won't boot, crashes, freezes up, pops up error messages or gives you the dreaded Blue Screen Of Death (BSOD), then it's unstable. Raise the voltage one notch at a time until it becomes stable again (check CPU load temps each time). For safety's sake, don't raise the CPU core voltage anymore than 10% to15% above default. Overclocking FAQ Overclocking is not recommended by any manufacture (especially Intel) and will void your warranty.  I do not advise anyone to follow these instructions unless they are willing to assume all associated risks.  I have consolidated in this document information that I've learned while overclocking my own system or that I have read about the experiences of others.  Overclocking can damage your system.  Working inside your power supply or wiring 110 volt fans can cause serious personal injury if done by the inexperienced or without the proper precautions.  If you're unsure or in doubt about any of these procedures, seek professional advice.  I am providing this document for informational purposes only. So you want to overclock a Celeron? You've read a few post, maybe visited a few web sites.  Everyone is reporting their success and claiming fantastic speeds from a lowly 266 or 300 MHz CPU.  You're excited at the prospect of a high performance CPU for, essentially, small change and you want to get in on the action.  The speed of a P2-400 or -450 for $90 or $150 sounds too good to be true.  But wait, they're talking about S-codes, multiplier locking, Pin B21, CAS-2, and other esoteric terms.  Names like Deschutes, Klamath and Mendocino are bandied about while you wonder what these words have to do with computers.  Now you're confused.  How hard is this going to be?  Is it worth it?   Do you need to be an Electrical Engineer to overclock a Celeron?  In a word, no.  With the right hardware and a little luck, it should be a snap. Why is the Celeron so overclockable?   As you may know, a given chip design is used for CPU's of many different speeds.  The P2 and Celeron designs are named after Western US counties: Deschutes, Klamath and Mendocino.  More on this later. In theory, a CPU is tested first at it's maximum speed.  The ones that pass the testing process at this speed are marked as such and sold as top-of-the-line CPU's.  Those that fail at the fastest speed are tested at successively lower and lower speeds until they run reliably.  These slower cores are then marked with the speed at which they passed the testing process and sold as slower processors.  At least, that's the theory.  No one really knows how Intel decides which cores get marked for a given speed.  Several other factors, such as customer demand and production quality, affect how many processors of each speed are produced. A CPU of any given speed can usually be made to run somewhat faster if one is willing to play around with the motherboard settings. This is the overclocker's bread and butter.  Now, through a convenient turn of events, Intel has produced a CPU with an unusually high capacity for overclocking. Intel has long controlled the high-end CPU market while it's competitors, Cyrix and AMD were gaining market share in the low- and mid-price range because of the popularity of lower priced PC's.  Intel finally realized what was happening and wanted to recover the low ground while also keeping the high end market (can you say "total market domination"?).  When Intel designed the CPU core for their newest line of processors, the P2, they changed the way the CPU was mounted.  All P2's are mounted on a circuit board, called an SECC (Single Edge Contact Cartridge), that plugs into a special, patented CPU slot (Slot 1) similar to a PCI slot.   [Intel calls the Celeron packaging a SEPP (Single Edge Processor Package) but it's still compatible with the Slot 1 connector, go figure.]   AMD and Cyrix do not have a Slot 1 CPU, so if you want high-end speed, you need to buy an Intel processor.   Thus the high-end market is preserved for Intel.  Now, Intel needed a cheap Slot 1 CPU to corner the low-cost PC market. Enter the Celeron line. To reduce production costs, Intel left out the expensive Level 2 cache.  Also, to eliminate design costs, the original Celerons (C266 and C300) used the same CPU core as the new 350-450 MHz P2's (code name Deschutes).  [Remember, design costs account for a huge percentage of the total cost of a CPU.  Once in production, it costs exactly the same to manufacture a core destined for use as a 266 MHz processor as it does to use that same core in a 450 MHz processor.]  Many media pundits immediately dubbed the Celeron a backward-stepping piece of crap because of the lack of the L2 cache.  Later, perhaps due to the poor reviews from hardware critics, Intel released the Celeron 300A and 333 with 128 Kb of built-in cache. Again, they used basically the same core design with some modifications to incorporate the on-die cache.  The C300A and the C333 modified Deschutes core carries the code name Mendocino.    Since Celerons use a Slot 1 motherboard, you can't upgrade to one of Cyrix's or AMD's fast new CPU's later, when prices come down.  They don't have Slot 1 CPU's and Intel has the patent.  Now Intel has again regained a foothold in the below-$1000 PC market and insured that the upgrade dollars also come home to Papa Intel too. Here's where it gets interesting.  The fastest P2 CPU's (350 to 450) require a relatively new type of Slot 1 motherboard with the BX chipset.  The BX motherboard runs at a bus speed of 100 MHz.  They can also run at 66 MHz bus which allows them to accept slower P2 CPU's (233, 266, 300 and 333) and Celerons. The Celerons are supposed to be used on the earlier EX and LX generation of Slot 1 motherboards which run at 66 MHz only.  Since the Celerons have the exact same core as the new architecture P2 CPU's,  there's nothing to stop you from setting the bus to 100 MHz and running a Celeron at 400 or 450 MHz. People started buying BX motherboards and Celerons and overclocking the hell out of them by setting the bus speed to 100 MHz. A chip meant to run at 266 running at 400 MHz and more was unheard of previously.  It's all because Intel is trying to capture the low-cost CPU market without the R & D costs of a new chip.  It's really a marketing stroke of genius when you think about it.  Produce one type of CPU.  Take the best ones, add 512 kb of fast, expensive cache and sell it as the top-of-the-line CPU for $700+.   Take the rejects, leave off the expensive L2 cache and sell them as cheap Celerons.  Except they're too smart for their own britches.  The production yield of 450 MHz cores is too good and the "rejects" are too few and far between.  Because they want to flood the market with $100 CPU's, they have to mark them as 266 to 333 MHz Celerons and sell them cheap anyway.  It doesn't cost them any more since both chips came off the same production line.  Because the P2-450 market is relatively small compared to the low- and mid priced market, the demand is greater for Celerons. What does stepping mean? Celerons come in four flavors.  The C266 and C300 without L2 cache and the C300A and C333 with 128 Kb L2 cache.  Each type of Celeron has several slightly different variations, called a "stepping".  Stepping 0 (zero) cores are the original production run.  When minor imperfections (bugs) are found in the instruction programming (micro-code) of the core or in other parameters of the chip, they are fixed and the next batch of cores will incorporate the changes.  This batch will be identified as stepping 1.  If another change is required later, the stepping number will be incremented again.   As each successive refinement to the chip is made, the next higher stepping number will be assigned.  For many reasons, one stepping may be easier to overclock than another, but usually the higher stepping cores make the best, most stable CPU's. What is an S-code? An S-code (Intel actually calls it an S-Spec.) is a 5 character designation beginning with 'S' used to identify the various different types, stepping, voltage and packaging of Celerons and other Intel processors.  There are currently 14 (as of  27 Sep 98) different S-codes for the Celeron family of CPU's.  OEM packaging is just the SEPP in  a plastic container.  There is no heatsink/fan attached, so you need to buy your own.  The warranty, if any, is usually only for 30 days and from the vendor, not Intel. The retail Celeron (sometimes also called a "boxed" Celeron)  comes in a cardboard box with a pretty good heatsink and fan already attached.  You also get a Certificate of Authenticity and an Installation Notes booklet in 11 languages, a cute sticker for the front of your computer and, most important, a three year warranty from Intel.  The S-code can be found on one end of the retail box or on the back, left side of any Celeron SEPP printed circuit board. C266  (Deschutes core without cache) ---------- SL2SY    Stepping 0  OEM SL2QG   Stepping 1   Retail SL2TR    Stepping 1  OEM SL2Y3    Stepping 2   Retail SL2YN   Stepping 0   Retail C300  (Deschutes core without cache) ---------- SL2YP   Stepping 0  OEM SL2Y2   Stepping 1   Retail SL2X8   Stepping 1  OEM SL2Y4   Stepping 2   Retail SL2Z7   Stepping 0   Retail C300A   (Mendocino core with 128 Kb L2 cache) ---------- SL2WM  Stepping 0  OEM SL32A    Stepping 0   Retail What is 'multiplier locking' and 'bus locking'? No processors since the early 80486 CPU's have taken the motherboard bus clock and used it internally at the same speed.  Remember the 486DX2?  It took the 33 MHz bus clock from the motherboard, multiplied it by 2 and ran at an internal speed of 66 MHz.  Modern, BX-chipset motherboards now provide a 66 or 100 MHz bus clock to the Slot 1 connector.  Today's Celeron and Pentium II processors multiply this to achieve their designated speed.  Without multiplier locking, circuitry inside the processor reads the multiplier jumpers on the motherboard via the Slot 1 connector.  Depending on the setting of these jumpers (or BIOS setting for the Abit boards) the CPU then multiplies the clock by 3.5, 4, 4.5 or 5.  Multiplier locking forces the CPU to use a multiplier that is pre-determined by Intel, ignoring the settings on the motherboard.  All Celerons are multiplier locked.  The C266 is multiplier locked at 4; the C300 and C300A is locked at 4.5; and the C333 is locked at 5. Multiplier limiting (only affects P2-350/400 processors made before mid-August '98) uses a signal from the motherboard to detect the bus speed and then places an upper limit on the multiplier based on the bus clock speed.  For example, with the bus set to 66 MHz, the processor can be set to a higher multiplier than it can when the bus clock is set to 100 MHz.  In effect, this limits the CPU to a maximum internal speed while allowing lower speeds.  With a 66 MHz bus, a "multiplier limited" P2 would accept higher multipliers than at 100 MHz.  [The BH6 BIOS has a setting under the SoftCPU menu called 100/66#SEL.  With the LOW setting you can defeat the clock limitation on certain P2 processors.  It will not work on the newer 400's and 450's and it will not unlock the Celerons.]  Intel says it uses multiplier locking and multiplier limiting to prevent unscrupulous retailers from re-marking processors to higher speeds. Bus locking is a myth, at least at the present time.  If it was implemented, it would prevent a processor from being used at a higher bus speed than it was designed for.  For example, since all Celerons are meant to use a 66 MHz bus clock, bus locking would prevent the CPU from running at any other bus speed.  Since bus speed is set on the motherboard,  Intel would need to design and incorporate special circuitry in the CPU to detect the bus speed and compare it to the "proper" clock rate.    Which motherboard should I use? There are basically two motherboards of choice for overclocking a Celeron, the Asus P2B and the Abit BH6.  The BH6 is by far the most popular with owners of the C300A for a couple of reasons.  First, it's the only motherboard that doesn't need a BIOS upgrade to recognize the C300A.  Secondly, it allows you to increase the CPU voltage from the BIOS SoftMenu.  This feature is particularly attractive since many C300A CPU's need a voltage higher than the default setting of 2.0 volts to be completely stable.  Additional features that make the BH6 popular are it's lower cost, BIOS SoftMenu setup for all settings and an additional PCI slot. In all fairness, the Asus P2B is also a very good board.  Though it costs about $40 (US) more, some staunch Asus supporters maintain that the P2B is more stable and has a higher success rate when overclocking.  The P2B does not have any built-in provision for changing the CPU voltage if it's necessary to do so, but it does have 3 ISA slots for those legacy ISA cards while the BH6 has only 2 ISA slots.  The biggest drawback to the P2B is that you need to flash the BIOS to the newest version (1005) in order for it recognize the C300A.  This can be problematic, to say the least,  since you need a CPU to flash the BIOS and it won't recognize your CPU until you flash the BIOS.  Catch 22. There are other motherboards that can be used, however, I recommend at least considering one of these two if at all possible. What about cooling? There are two aspects of system cooling that need to be considered, case cooling and CPU cooling.  The power supply fan alone normally does not provide sufficient air flow to eliminate heat build-up inside your case.  Hot air trapped in the case forces all components to operate at higher temperatures and reduces the effectiveness of convection cooling throughout your system.  Many overclockers find that heat is their main enemy, especially if you find that you need to raise the CPU voltage.  There are several things you can do to ensure that your case stays cool. First, check the direction of air flow from the power supply fan. The best cooling is obtained by having the power supply fan draw air out of the case.  If it draws air into the case, you may want to try reversing it. It's a simple procedure than can make a significant difference in case temperature. [Caution:  Capacitors in the power supply can store a charge even after the power has been off for several hours.  Make sure that the unit has been unplugged for 24 hours or more.]  Remove the supply from the case and remove the cover.  Most power supply fans are held in place by four screws.  Remove these four screws and flip the fan over.  Generally, both sides of the fan will have a set of holes so you should be able to re-attach the fan with the same screws.  Reassemble and install the power supply.  You should see a drop of several degrees inside the case just from this simple, free procedure.  Opening the power supply will probably void the warranty on it so, if you're worried about that sort of thing, you'll be relieved to know that there are other things you can do to lower your case temperature. Adding a second fan is a good idea even if you aren't overclocking.  Many cases provide a location at the lower front that is designed for a second fan.  Even if your case doesn't have a ready-made mounting point, you should be able to find a spot to install a second fan.  Depending on the type of connector your fan has, you can plug it into the motherboard fan connector or use one of the extra drive power cables for it's 12 volt supply. Leaving the case cover off is also a possible solution to overheating.  Though not ascetically pleasing, it is a free solution that many overclockers employ. Now that your case is maintaining a near ambient temperature, you need to think about the CPU.  If your system crashes or seems to become unstable after a few minutes of operation, you may find that heat build-up is the problem.  The fan and heatsink that is attached to retail Celerons is usually adequate to achieve the 400 or 450 MHz speed with the C266 or C300A.  If you bought an OEM Celeron or if you're having suspected heat problems with your CPU, you'll need to buy a good heatsink and fan combination and install it on the CPU.  Many vendors offer cooling packages with heatsinks and one, two or even three fans.  One vendor (STEP-ThermoDynamics) even offers an electronic peltier system ($85 US) and another (Kryo-Tech, mentioned at Tom's hardware site) offers a $500 refrigeration system.  While these expensive cooling systems work very well, most people find that a simple heatsink setup with one or two ball-bearing fans will provide all the heat dissipation that your CPU needs.   How do I overclock? First, set up your system and get it running at it's normal speed.  Set the SoftMenu or the jumpers as directed in your motherboard manual.  Install all your peripheral cards and software and test out the system.  Run a few benchmarks at the standard speed so you can compare the before and after results.  Only when you're satisfied that the system is behaving as it should and that it's stable at the rated speed, should you begin to push the performance envelope of your system. Now you're ready.  Neither the Asus or the Abit motherboards require you to cover pin B21 on the Slot 1 edge connector.  It is ignored by the motherboard.  Most other motherboards do require you to cover this pin to fool the bus speed setting circuitry into selecting the 100 MHz speed. On the Abit boards you should reset your system and enter BIOS setup.  Change the following options in the CPU SoftMenu: CPU Operating Speed:   User Define - External Clock:  100 MHz - Multiplier Factor:   x4  (or 4.5 for the C300A) - AGP/CLK:   2/3 Speed Hold Error:   Disabled [Note: I don't have an Abit motherboard so the SoftMenu setup is unfamiliar to me.   These are the settings recommended by Andy Drake's web site.  If anyone has something to add or correct, please contact me.] On the Asus P2B you have to change a jumper on the motherboard.  If you are set for the 66 MHz bus speed (as you should be if you followed the advice at the beginning of this section), you should only need to change one jumper.  Power down and unplug the power cord.  The jumper block that you need to set is located just above the primary IDE connector and it should be labeled "BUS FREQ".  Your current setting for 66 MHz should be: FS0 1-2 (pins closest to CPU), FS1 1-2 (pins closest to CPU), FS2 2-3 (pins away from CPU).  To set the bus to 100 MHz you need to change FS2 to 1-2 also.  Now all three jumpers should be on pins 1-2, the pins closest to the CPU. That's it.  If it works when you power up, you'll be at your new, overclocked frequency.  A C266 will be 400 MHz; If you're lucky, a C300 or C300A will be at 450 MHz; and, if you're really, really lucky, the C333 will be at 500 MHz.   If your computer completes POST (Power On Self-Test),  boots into Windows and seems stable, try running some applications.  Run a benchmark or two.  Let it stay on for several hours, cycling a game demo or benchmark.  If it acts normally, except FASTER, of course, congratulations! If it doesn't work at first, don't worry (yet), there are several things you can try before you give up and admit that you've got an "unlucky" CPU.  Read on. What if it doesn't work? There are many things that can be done to coax a stubborn CPU into working.  I'll try to mention as many as I can here.  Above all, don't give up until you have exhausted all of your options.  Some of the things you can try are free or low cost, while others may require replacing some expensive components.  Whenever possible, try to eliminate the cheaper options first.  Then, if you suspect you may need to buy a new DIMM or video card, try to borrow one from a friend first or try your CPU in another, successfully overclocked system.  Remember, it might not be the CPU at all, but something else in your system that's giving you problems. Heat As mentioned in the section on cooling, heat build-up is one of the most common problems.  It manifests itself usually after several minutes to an hour after start up, especially when running CPU intensive applications.  If you system won't POST (Power On Self-Test), heat is probably not one of your problems.  1.  Try leaving the case open with a table fan blowing into the case.  If the system stays up longer or seems more stable with the table fan and open case, try some of the cooling methods mentioned above.