Warning Overclocking can and will reduce the life of your central processing unit(cpu) PCHF is not responsible in any way to damage done to your computer due to overclocking in any way shape or form. All advice given is that, Advice. Overclock at your own risk



Q: FSB , Processor, Memory, PCI, & AGP Speeds - How do they work together?? ?
A: All these speeds can be source of confusion for many newbies and veterans to overclocking alike and also to those just wanting to build a PC. Here's a brief explanation that will hopefully help.

System Clocking (aka Front Side Bus speeds):

All of the major components on the motherboard - Processor, Memory, PCI, and AGP devices are connected via signal busses that require some form of external clock signal to set their operating speed and to synchronize them during operation. Unfortunately, they don't all operate at the same speed. Processors and Memory run at higher speeds than AGP (video cards) and PCI (io) devices. Also, processor and memory speeds can vary dramatically from processor make/model to another, while AGP and PCI speeds are typically fixed. Processor external clock speeds are set by the Manufacturer (Intel, AMD) and vary by processor model. Common processor external clock speeds are 100 MHz, 133 MHz, 166 MHz, 183 MHz, and 200 MHz. The AGP bus speed is fixed at 66.66 MHz, and the PCI bus speed is fixed at 33.33 MHz by industry standards.

When building a PC or attempting overclocking, all these speeds need to be kept in mind and controlled and matched appropriately through jumpers on motherboards (older boards) or through software settings in the BIOS (current boards). When building a PC or overclocking one, the external processor speed can be set using the BIOS setting screens. Some motherboards allow only specific settings mentioned above, while others allow settings in 1 MHz increments. These fine-grained settings allow you to overclock by changing the clock speed in small increments until you hit the highest speed possible without experiencing instability. Note that machines from Compaq, Dell, HP, etc seldom provide users with the ability to make these adjustments.

PCI and AGP bus speeds can often be locked at their ?spec? speeds or allowed to rise in proportion to the processor FSB speed depending on the settings in the BIOS. For example if you allow the PCI and AGP speeds to increase proportionately as you raise the FSB speed when trying to overclock the CPU, you may wind up overclocking the video card or PCI devices beyond their capability, thereby causing them to fail even though the processor is still fine. Under this condition, you?d probably go into the BIOS and lock the AGP & PCI speeds at 66 MHz and 33 MHz respectively to keep them ?in spec?. If on the other hand, your video card and PCI devices can tolerate the higher clock speed without giving errors or causing instability, then let the speeds adjust and be happy that you have great components!

The bottom line is the main system clock setting, which is usually labeled ?Processor Speed?, FSB Speed, etc. in the BIOS is the primary adjustment and other components take their settings from this one. Clock dividers are used to set these other speeds as a ratio of the FSB speed.

Processor speeds:

To confuse matters a bit, internal processor speeds are quite different from the external clock speeds you set in the BIOS. They are often advertised or reported in terms of internal bus and clock speeds and in reality, they are a multiple of the external clock speed. For example the Pentium 4 is considered a quad-pumped processor, so internally (inside the processor chip, that is) the processor bus runs at 4 times the external clock rate. A Pentium 4 with an external clock speed of 200 MHz is really operating at an internal FSB speed of 800 MHz. The effective processor speed is model dependent and based on an overall multiplier. For example a model 2.4B Pentium 4 chip (rated at 2.4 GHz or 2400 MHz) uses a 133 MHz external clock, runs its internal FSB at 133x4 = 533 MHz, and uses an internal core multiplier of 18 thereby achieving a rated speed of 2400 MHz (133.3 MHz x 18 = 2399 MHz).

Memory Speeds:

Memory speeds are also related directly to the Processor external (and internal) clock speeds. Current technology DDR (Dual Data Rate) memory modules are rated by their speed and bandwidth. Speed is how fast they run, bandwidth is how many megabytes per second can be read/written to the module. Since DDR moves data on both the rising and falling edge of the clock, speed ratings are expressed in terms of the external clock frequency times 2. So if you are running a 200 MHz system clock (FSB speed), you need memory rated at 400 MHz or DDR400 memory. These same modules are labeled and sold based on their bandwidth. Since memory busses are 8 bytes wide, memory bandwidth = clock speed x 2 x bus width (8). Therefore, a DDR400 memory module is generally labeled a PC3200 memory module (200 MHz x 2 x 8 Bytes = 3200 Megabytes/second).

Common Memory Modules and Speeds:

Thanks to Bobaroo330 for providing this data regarding common memory modules

PC1600 DDR xxx = (100 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 1600 MB/s available bandwidth.

PC2100 DDR xxx = (133 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 2128 MB/s available bandwidth.

PC2400 DDR xxx = (150 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 2400 MB/s available bandwidth.

PC2700 DDR 333 = (166 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 2656 MB/s available bandwidth.

PC3000 DDR xxx = (183 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 2928 MB/s available bandwidth.

PC3200 DDR 400 = (200 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 3200 MB/s available bandwidth.

PC3500 DDR 433 = (215 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 3440 MB/s available bandwidth.

PC3700 DDR 466 =(233 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 3728 MB/s available bandwidth.

PC4000 DDR 500 = (250 MHz Operating Speed) x (2x Rising & Falling) x (64-bit Bus) / (8 bits per byte) = 4000 MB/s available bandwidth

Real World Example:

So you want to build a new overclocking rig. Perhaps something that uses the new ?C? revision P4 processor. What components do you need to get it off the ground? Chances are you will be looking at the 2.4C processor as it?s a really great CPU for the money and overclocks very well. So lets start there.

The P4 2.4C is a quad-pumped processor designed to run at an external clock speed of 200 MHz. Internally it runs its memory bus at 4 x 200 or 800 MHz. Internally the core uses a multiplier of 12, so the processor is designed to run at 12 x 200 MHz or 2400 MHz.

First off, you need a motherboard capable of 200 MHz clock or higher. A nice board using the Intel Canterwood or Springdale chipset will do. I won?t suggest any particular board ? ASUS, MSI, ABIT, EPOX, and others all make good ones.

Next you need memory - memory that runs at 200 MHz or faster. DDR memory runs at 2 x the external clock speed of the processor, so you need at least DDR400 memory. It is also called PC3200 memory (remember 200 x 2 x 8 = 3200 from our discussion above). This of course is if you plan to run at the stock speed of 200 MHz. However, if you plan to overclock the system, you will be raising the FSB clock above 200 so you should plan on using memory that is rated as fast or faster than your expected overclock speed. PC3500 memory is rated for clock speeds up to 218 MHz, while PC3700 is rated to run at up to 230 MHz. Of course depending on the quality of the memory you buy, and the memory timing and voltage tweaks you make, you may be able to run them higher than their rated speed too. Memory timing and voltage are subjects for another FAQ.

When overclocking, remember that for every 1 MHz you raise the FSB clock, you are increasing the core processor speed by its multiplier (12 in our P4 2.4C example). So if you start out at 200 MHz, then bump the P4 2.4C up to say 210 MHz, you are raising the CPU from 2.4 GHz up to 2.52 GHz. If you are lucky and can get your clock up to say 255 MHz, your processor will be running at 3.06 GHz! Remember, though, your memory will also be clocked at 255 MHz. So technically you need memory rated slightly above PC4000 to get there (255 x 2 x 8 = 4080). Some very high quality PC3700 memory can actually run that fast with careful treatment (aka burn-in) and timing experimentation. PC4000 rated and faster memory modules are just starting to show up on the market, though most contain lower rated speed chips that have tested to run stable at the higher speed.


Q: Can I overclock a name brand computer?
A: In most cases, No. You?ll have to see if there are jumpers on the motherboard or settings in the BIOS to change the CPU bus frequency and/or the multiplier if your CPU will allow it.

What you need to do is open the computer and see if you can find a model number on the motherboard. Sometimes there will be a sticker on the end expansion slot, ISA or PCI, or it may be printed on the motherboard. IF you can find some numbers on the board, put them into a search engine and see if it will give you a link to the manufacturers website. Once you know who makes the board you should be able to obtain a manual for the specific board and see if there are any options for changing the CPU speed.



Q: How do I show off my overclock??
A: The goal of overclocking is to make your hardware faster than it comes stock. Increasing Mhz and decreasing timings all lead to a faster computer. But how does one show off their newest and greatest overclock? Benchmarks!

Benchmarks are a way of comparing your computer to other computers, or your stock settings to your new overclocked settings.

Here are a list of just a few commonly used benchmarks

SioSoft Sandra
FutureMark 2004
3d mark 2001
3D Mark 2004
Super PI
Hexas PiFast

And The Top One Most People Use Is
CPU-Z

Each of these benchmarks respond in their own way to overclocking changes, but the general rule is this. The faster it is the higher you score.

When showing off your results there are a few unwritten rules most follow.
1) Include full system specifications.
2) Post a screen shot of your benchmark

I I figured I would update this a little since it is a little outdated...This will be an ongoing piece of work.If you have anything to add please free to add or ask a question if you find something hard to understand.


I will be using my AMD 4200+x2 for this part..As I have not used an Intel since the Plll's

To begin when overclocking you need a good case. A good case will help dissipate heat faster. I just bought an Antec 900 case. I found this to be an excellent case as it has 5 1200mm fans and a huge 200mm fan. The new version also has 2 nice rubber ends in the back for easy water cooling modifications..You can see the specs for this case here. Newegg.com - Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail ...

To begin we have the 4200+x2 stock speed at 2.2ghz.
The first thing you will want to do is "burn in" the cpu at this speed for a good 12 hours with Prime 95 which you can find here Free Software ..
Since this cpu has 2 cores you will want to run 2 instances of the program. You will want to monitor your temps as well so download speed fan from here. SpeedFan - Access temperature sensor in your computer


Now that we have the cpu "burned in" we can start upping the front side bus from within the BIOS.. Since the 4200 has a front side bus of 200 we want to go slowly, always remember slower will always yield better results in the end. I know how it feels to just want to go full on but this will not yield a very high and stable overclock.

Now change the multiplier to 11 on your cpu multiplier..
Next up the FSB to 204.. Run Prime 95 again for 4 hours monitoring your temps. You do not want to go above 65c while doing prime 95.
Next we will up the FSB to 208.. Again run prime 95 for 4 hours.
Next go to 212. This time only run prime 95 for 2 hours..
Next go to 217. Run Prime 95 for 2 hours again.
Let you cpu rest for a good day ( you can do things on the pc but do not use Prime 95 for a day)
Next we will go up to 221. Run prime 95 for 1 hour. You may have to up your V-core by a couple volts. It should not be just yet but if you cannot get past the BIOS screen then you should up the v-core only by a couple of points.
Now is the big jump where you will more than likely up your v-core to around 2.6 this is when your heat will come in..You will really not notice the heat going up until you up the v-core.
We will take the FSB up to 235. Run prime 95 for 1 hour watching your temps. You will not have to up the V-core again..
Next take the FSB up to 239. Run prime 95 for 4 hours again and wacth temps every now and again..
Let you cpu rest for a day again.

If your temps stay below 45c under these temps keep going. If they go higher than 47c stop here and you will have a stable oc that you can run 24/7

Next we will go up to 245..Run Prime 95 for 1 hour let your cpu rest for a good 2 hours and run Prime 95 again for an hour.
Your cpu and motherboard by now are used to upping the FSB.
You can continue to go up by 4 or 5 points but you can jump to 249. Most will stop here as Temps will be an issue.
If you got lucky like I did, you can keep going until you hit a FSB to 255 on Air alone..This is now a 2.8 ghz monster cpu that was pretty cheap to buy.

Always remember to go slow.Do not rush or you wont get near 240. This is why I buy cheaper CPU's and take a week to overclock then so that I can have a very high FSB that compares the cheaper cpu to a nice AMD FX-60.
The Slower the better. The more you run prime 95 the better as you cpu gets used to the higher clock speeds and does not throw a sweat at it

Also remember your case and Cpu heatsink and fan will play a very big role in how high yo can get before Failure sets in and you have to reset the CMOS..

Do not scrimp on the case nor the cpu cooler as these are the most effective ways of keeping that new monster overclock stable..Most just overclock for a couple hours to do benchmarks. I overclock to save myself money.

Again this will be a work in progress. Next we will update the overclocking proccess for your Video Cards.

Very nice guide!

Considering using it to take my AMD Athlon 64 X2 5600+ to 3.2GhZ.

Thanks!

thnx for this

just wondering, have u had any time to write one on RAM or Video Card overclocking?

thnx, Ash