Guide To Overclocking Your PC

Before we even begin...

Overclocking Can Destroy Your Equipment! Neither I, nor AMD/Intel, nor your mobo manufacturer will do anything if you lose your investment by clocking it above max documented speeds!

This guide will, however, miminize this risk - so if this is your daddy's computer, dont mess with it

A successful overclock is simply one that is stable. But this cannot be considered fun or exciting - a fun or exciting overclock is stable and gives you noticably higher performance. A "friggen sweet" overclock is nothing more than a fun or exciting overclock that just happens to have numbers that impress your friends.

A good overclock requires adequate power to keep the higher clock stable. Without this extra power, you will be prone to anything from random computer errors to fried chips - the latter, of course, being extremely rare and mainly due to human carelessness. But higher power means more heat generated, so...

A good overclock requires adequate cooling. This is not to say that you need to upgrade your cooling - a small overclock is extremely safe, and will just give you a bit of extra juice that can always come in handy. On the flipside, many of today's newer processors (especially high-end AMDs) are shipping with rather beefy and nice heatsink/fans that allow for tons of leeway in terms of overclocking.

The number 1 way to make sure you are successful - read through this guide completely TWICE, and take notes as you go. Not sure about something? Read it again. Even a budget computer is $500 - not something we want to throw away by refusing to give up a half an hour of our lives.

In the beginning, there were BIOS options...

So we'll start off by listing the options we have to work with:

* FSB/HTT (Front Side Bus, aka HyperTransport on AMD machines)
* Multiplier(s)
* Voltages
* Memory Timings
* Memory Divider
* Bus/Clock locks

We'll go over what each of these is and how it affects the overclock before starting any tweaking - i find that a better understanding of the real working of parts makes overclocking easier and more fun.

FSB

This is the speed at which information travels between the processor and the chipset, ram, etc. It also directly affects processor speed. This is the major tweak for increasing CPU power and performance. An increase in this has effects many times greater on the CPU speed. On some AMD64 systems, the HyperTransport bus speed has the same effect. On others, it's called the LDT bus. Please refer to your motherboard documentation to find out which.

Multipliers

There are many multipliers in your PC - we're worried about 2 of them for now (other important multipliers will be covered later). 1 is the chipset multiplier. The second is the CPU multiplier. Each does the same thing - they increase the operating frequency of the chipset and processor respectively, by multiplying the FSB speed by the multiplier value. Before you get any bright ideas - most processors have a locked multiplier, meaning you can lower it from stock, but you can't raise it. Exceptions to this are AMD FX and Intel EE chips.

Voltages

As clock speeds get too high, components need more power. And when not enough power is given, they produce errors or wont even work at all. We fix this by alloting them a higher voltage. However, this does two things. For one, it produces more heat. This is of immediate concern, because it causes stability problems. The second consequence of increasing voltages is decreasing the lifespan of your hardware - but rest assured that if you do not overvolt the processor more than 15% and the RAM no higher than 3.0 volts, it will last for the same amount of time as they're usually useful. Of course, lower is always better.

Memory Timings

These days, they're for showing off. For the most part we will be utilizing these not for increasing but instead for decreasing - the effect will be increasing stability rather than an almost unnoticably subtle increase in performance. Memory timings are latency values - they determine how fast information goes through the memory. Decreasing these timings reduces latency somewhat, but will not make things go terribly faster.

Bus/Clock Locks

Buses such as the PCI, AGP, PCI-e, and SATA buses are also dependent on the FSB. Unfortunately, these periferals don't like going must faster than default. They tend to fail almost right away, say even after such a minor overclock as 15mhz on the FSB. Fortunately, most motherboards (at least any worthwhile for overclocking) will have 1 of 2 options: you may be able to alter the multipliers for each of these buses, bringing them back down to a working frequency; you may instead have the option to "lock" these buses, meaning that they will be run by the motherboard at original speed and will automatically not be affected by and FSB increases we make. This makes things much easier. PCI should always be 33 Mhz, and AGP should always be 66 Mhz. Changing this too much can lead to hard to diagnose DMA problems that will crash your system without fail.

Memory Divider

I will be talking about DDR RAM in this tut. I assume you dont use SDRAM or RAMBUS. If you use DDR2, tough break - Ive never owned it, and dont know a thing about it. In any case, this ram runs at double your FSB (DDR means double data rate, it runs double the FSB. simple, eh?). However, when memory runs too fast it fails. To keep the maximum CPU speed, we can use a "memory divider" (essentially a memory multiplier or sorts) to lower its speed and have it running stable again. Fun!

How to use what you've learned:

CPU speed = FSB x CPU-Multiplier

Everything else will be changed as a consequence of the alterations we make for the processor - they are all secondary.

FSB/HT (Hyper Transport) = FSB x Chipset-Multiplier

- Note: The 800mhz or 1000mhz rated speeds on motherboards refer
to the FSB of the processor plus some voodoo. Intel 'quad pumps
their FSB to quadruple the amount of data going over the bus
without actually affecting the clock rate. Divide by 4 for P4s to find
the correct setting. AthlonXPs 'dual pump.' Same thing, but only
twice the throughput. Divide by two. Athlon64s use the LDT bus
times the multiplier.

Before we dive in, we have to think about the optimum outcome of this overclock. We want the highest CPU speed possible. We want a working chipset. We want the best memory performance possible at this CPU frequency. We want stability. We don't want to overheat. This is not as tough as it looks.

Overclocking Step 1 - Finding Maximums

FSB

First, we need to find out maximum FSB. This affects how we clock our CPU and how we deal with our RAM. Of course we know that components running way too fast will crash and burn. So set the CPU multiplier very low to 5 or so (this takes the CPU out of the failing equation). Set the RAM divider to half (1:2), taking it's failure out of the question. Set the chipset multiplier to 2. Lock the PCI, AGP, PCI-e, and SATA buses. If you cannot lock them, this will severly limit your overclock. Now begin upping your FSB.

When overclocking, WORK SLOWLY!!! It cannot be stressed enough that recklessness will break things. So when we increase FSB, we do so 5mhz at a time. We save and exit BIOS, and restart the computer. If Windows boots, we claim success (for now). Once you reach a FSB clock that fails to boot into Windows, start lowering the clock in 1mhz intervals until you find the max possible that Windows boots at. WRITE THIS NUMBER DOWN, LABEL IT "MAX-FSB".

CPU

Max CPU speed is, of course, the end-goal in overclocking. Keep the memory divider on 1:2. Keep the FSB at the maximum you just found. Now, up the multiplier in intervals of 1 (ignore multipliers with half-options, eg 4.5, 7.5 - they cause more harm than good), restarting each time to see if Windows boots. Keep increasing until windows fails to boot. WRITE DOWN THE HIGHEST MULTIPLIER THAT WORKED WITH THE MAX FSB, LABELING IT "HIGHEST-WORKING-MULTIPLIER".

This is not the end. It is entirely possible that the next-highest multiplier will work with only a slightly slower FSB. And 230x9 (FSBxCPU-Multiplier) is slower than 210x10. So we increase the multiplier by 1, and lower the FSB in 5mhz increments, restarting to see if Windows boots. Once it does, start increasing the FSB in 1mhz increments until Windows fails to boot. WRITE DOWN THIS SECOND-FSB RATING ALONG WITH THE USED MULTIPLIER, LABELING THE MULTIPLIER "MAX-MULTIPLIER" AND THE FSB VALUE "HIGHEST-WORKING-FSB"!!! Keep increasing the multiplier by 1 and lowering the FSB until you run out of multipliers - this shouldnt require more than one repeat.

Now, determine the max CPU speed you can achieve. Multiply the combinations of the two options we have found.

* Option 1 is MAX-FSB x HIGHEST-WORKING-MULTIPLIER.
* Option 2 is HIGHEST-WORKING-FSB x MAX-MULTIPLIER.

Whichever comes out higher will be our new baseline-setting for our overclock. Congratulations - you have identified the fastest your CPU can go without failing to boot. This is not necessarily stable.

People may tell you to increase voltage at this stage - bad idea. Though overclocking enthusiasts such as myself do this to see the maximum speed we can get out of our processors, the gain is much smaller and the risk is substantially higher. We will deal with voltages later, for stability's sake only.

Overclocking Step 2 - Bring the Rest Up To Par

Chipset

We still have the chipset (HyperTransport) multiplier set to 2. See that FSB youre using? Divide your rated FSB (1000 or 800) and divide it by your FSB, and round-down. This is now your chipset multiplier. For instance, if I find my max FSB to be 230, and my motherboard is rated for a 1000mhz HyperThreading, I take 1000/230 = 4.35. I then set the chipset multiplier to 4. Simple. You can try lowering fsb and increasing chipset multipliers and seeing what gets you the highest performance - the gains will be almost minimal for the sake of a novice, and the headache and amount of consumed time will be large.

Memory Dividers

You ever wonder why PC4800 RAM costs so much more than PC3200? Believe it or not, at stock settings they make absolutely no difference. These ratings are related to the max speed they are rated to be stable at. Each PCXXXX rating corresponds to the other common rating system, DDRXXX. PC3200 is the same as DDR400. PC4800 is the same as DDR600. Just a different rating system. This doesnt mean to suggest that having DDR3200 (DDR400, aka FSB 200) means you cannot increase your FSB - for two important reasons:

* Most memory will clock faster than its rating
* We can slow it down using dividers.

To do this, use your max working CPU config (FSB and Multi), and make the RAM divider 1:1. Restart and see if Windows boots. If not, take it down a notch, restart, and see if Windows boots. Continue until you see that lovely Windows logon page. If your FSB is much higher (50Mhz or more) than what your RAM is rated for, there's a chance it will not POST at all. Do not panic. Your RAM is probably ok. Locate your 'Reset CMOS' jumper and move it to the other pins. Wait a few seconds and move it back. Turn it on. DO NOT turn it on when the jumper is in the 'reset' position. You WILL fry your motherboard. If this happens, start with a higher divider after resetting the BIOS.

Now, increase that divider back up one notch, and also increase the RAM Voltagage in 0.1v increments. Restart, and see if Windows boots. If it does, increase the multi again and continue the cycle. If not, continue on. Once you reach 3.0 volts (this is probably your mobos maximum regardless), stop, and use the highest divider that works at this setting. If you reach the 1:1 multiplier at a lower voltage, good for you - you bought good RAM.

Overclocking Step 3 - Making it Stable

You can boot into Windows with the fastest possible CPU, and all the corresponding parts. Sweet! But you also own one of the most unstable pieces of electronics on the planet. Itll run as sour as a 1980s VCR. So let's fix this.

Lower the FSB 5%, and increase the voltage 1 or 2 notches. Thats it. Now run a game. Play something that has really taxed your system in the past - preferably a new-generation first person shooter. Does it crash? If not, you're done. Seriously. Go out and own the world knowing you have the same speed computer as your friend even though you paid less and your computer is older.

There are plenty of programs out there that will run background processes that make 100% utilization of computer resources. However, you are two things: 1) A novice overclocker who has done rather safe modifications, and 2) A gamer who is not going to be running 100% CPU utilization for 24 hours. Given these criteria, especially the latter, then stability in a game is good enough. If you ever get blue screens, just tab the FSB down or tab the voltage up. Be CAREFUL about the second option! Overvolting damages your computer, and causes overheating. If you have increased your voltage by over 3 selections in BIOS, then stop and just start lowering the clocks.

Thats about all I can think of for now. Yes, there are things we could go back on. Yes, there are other options we could tweak. Yes, we can get more speed out of this. I just made this quick and easy for us overclocking newbies and gamers who would rather spend a day shooting people than a day trying to get 1mhz more out of their PC.

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