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Overclocking Computer hardware develops at an outstanding rate but few have the budgets available to always buy the latest and greatest as such many shoppers look for equipment that can be overclocked, with the aim of increasing the performance beyond its original specification. This is often easier than many people think, the reason behind it is related to the manufacturing process. If we look at the types of components in question you will gain a greater understanding. Processors These days there are only two real CPU (Central Processing Unit) manufacturers, AMD and Intel. Processors are manufactured in FAB’s all around the world, essentially each batch made is qualified to see what performance it can produce, it is then graded, badged up and sold as the corresponding model. One batch may tolerate higher voltages and achieve faster speeds, these will be sold as the premium models. Those not able to withstand the higher speeds will be sold as the more standard models. How to overclock a processor The two main methods of clocking a CPU are the CPU Multiplier and the FSB (Front Side Bus). The speed of modern CPU’s is measured in Megahertz or Gigahertz, this frequency is created by multiplying the FSB by the Multiplier, for example a 10x Multiplier and a 100Mhz FSB would give a CPU of 1000Mhz (1Ghz). CPU Multiplier – Some CPU’s have a fixed multiplier, others are more flexible. Using the example above if you could increase the multiplier from 10 to 12 is would increase the CPU speed from 1Ghz to 1.2Ghz. These days CPU manufacturers usually lock the multiplier (preventing it from being increased) on all but their most expensive CPU’s (AMD’s FX series, or Intel Extreme Edition). Using the right hardware you can often work around this, many motherboards provide the flexibility required, these are often sought after by consumers as they are quick to gain a good reputation. Front Side Bus – FSB is controlled in the motherboard BIOS (Basic Input Output System). While it used to be very straight forward (as in the above example) modern systems are somewhat more complicated. Intel systems have their FSB broken down into 4 parts, so the number you are working with is multiplied by 4 to create the actual FSB. For example the Intel Core 2 Duo is focused on a 1066FSB, this is actually 266.5Mhz. In overclocking you would seek to push this further, if you go to 300Mhz for example your Front Side Bus would be running at 1200Mhz. The number sued to calculate the CPU speed is still the basic FSB (not the one increased). If we had a FSB of 300Mhz (1200Mhz) and a multiplier of 9x, the CPU would be running at 2.7Ghz. On Dual or Quad core systems there would be 2 of 4 cores running at this speed! CPU speed is not just related to the raw power, modern CPU’s use efficiency to achieve more per cycle. In addition they will use large amounts of CPU cache to speed up key instructions. Often when overclocing a CPU you will also need to manipulate a third value, the CPU voltage. When running at high speeds CPU’s need constant and steady voltage, a suitable motherboard will give you precise control. Memory Memory manufacturers such as Kingston, Corsair, OCZ etc purchase vast numbers of memory chips from manufacturing partners in the far east link Micron, Samsung and Hynix. Each batch they buy will be assembled onto a PCB (Printed Circuit Board) and tested. Those parts that meet the highest standards will be sold as premium products, those that pass quality control but can not feature the same high speeds will be sold as standard or value units. Memory speeds relate to three key areas. Front Side Bus (FSB) – Memory is often recognised by one of two identifiers the bandwidth or the FSB, these two are directly related, here are a few examples: DDR1 PC2100 = 266Mhz PC2700 = 333Mhz PC3200 = 400Mhz DDR2 PC5300 = 667Mhz PC6400 = 800Mhz PC7200 = 900Mhz The first number is the bandwidth; this is how much data you can squeeze into it. It is approximately 8x the FSB, so 8 x 900Mhz = PC7200. DDR actually standards for Double Data Rate, as such the speeds above represent twice the FSB that is actually being used. In the BIOS RAM speeds are often recognised by their standard speeds so PC7200/900Mhz will actually be running at 450Mhz. If overclocking you would seek to slightly improve the timings, so for example if the FSB could be increased from 450Mhz to 500Mhz you would run at PC8000/1000Mhz. Voltage – DDR2 has a standard voltage of 1.8v, when overclocking we need to provide stable power, this would mean that you often have to increase the voltage to about 2.1v. Latency – If you consider RAM as a giant spreadsheet, where data is stored for manipulation by the CPU then the latency represents the times taken to find the correct column, select the cell, read the data and then move to the next request. The lower the latency the faster the RAM, when overclocking you need to find the right balance of bandwith/FSB vs latency. Latency is controlled by the RAM’s SPD chip; on a high end motherboard you can control the latency manually. Video Cards The video card speed relates to its GPU core and its memory speed. Often the easiest overclock both of these values can often be adjusted by software, however not to the same dramatic extents as a CPU overclock can be. 10% can usually be done, but it does increase the heat generated by the card. Many video card manufacturers now offer pre overclocked cards, this option is very popular as they address the required cooling and provide sufficient warranty. |
