damian kardański overclocking and cooling 1. framework 1.introduction 2.quartz crystals in...

Damian Kardański

Overclocking and Overclocking and CoolingCooling

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Framework

1. Introduction2. Quartz crystals in controlling a system’s speed3. Beginnings of overclocking4. Overclocking modern PCs5. Cooling methods

Heatsinskso Passiveo Activeo Thermal interface materials

Liquid coolingo Heatpipeso Water cooling

Thermally advantaged chassis Processor duct

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Introduction

Overclocking - the process of running a computer component at a higher clock rate (more clock cycles per second) than it was designed for or was specified by the manufacturer

As clock frequencies in digital circuits increase, the heat generated by components running at the clock speed also increases.

Cooling - the process of removing heat from computer components.

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Quartz crystals in controling a system’s speed

Quartz crystal is silicon dioxide (SiO2) in crystalline form. Hard, transparent material, brittle, but with a little bit of elasticity

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Piezoelectricity:

Ability of some materials to generate a voltage when subjected to mechanical stress and to generate mechanical stress when subjected to a voltage.

Piezoelectricity was first discovered by Pierre and Jacques Curie in 1880 and it’s the essential feature of quartz that makes it useful in electronic circuits.

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The speed of a computer system is derived from the main motherboard crystal (always 14.31818 MHz) in conjuction with a frequency timing generator (FTG) or a frequency synthesizer.

Frequency synthesizer chips use phased locked loop (PLL) cicrcuity to generate synchronized processor, PCI, AGP, and other bus timing signal that are all derived from a single 14.31818 crystal.

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Beginning’s of overclocking

IBM PC AT (Advanced Technology) from 1984.To run the system a socketed crystal of 12 MHz or 16 MHz was used. The timer chip divided the crystal speed by 2 (speeds of 6 MHz and 8MHz). An 18 MHz or 20 MHz crystal could be purchased for $1.

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Overclocking modern PCs

Most modern motherboards allow to change speed, timing and voltage settings of computer components in the BIOS Setup.

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Processors run at a multiple of the processor bus (FSB/CPU bus/PSB) speed and the selected multiple is locked within the processor.

Example:Intel Pentium 4 3.2E processor running at 3200 MHZ on 800 MHz CPU bus (locked multiplier – 4).Increasing CPU bus speed to 832 MHz (4%) results in the increase of the processor speed to 3328 MHZ.

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Increasing FSB’s speed increases the speed of other buses (memory, PCI, AGP) by the same percentage.

Therefore, after increasing FSB’s speed, if the memory or any other component is unstable at the higher speed, the system will still crash, even though the processor might have been capable of sustaining it.

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Heatsinks - passive

Heatsink – an object that absorbs and dissipates heat from another object using thermal contact.

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Heatsinks - passive

Heatsinks are rated for their cooling performance. Typically, the ratings are expressed as a thermal resistance in degrees centigrade per watt (°C/W), where lower is better.

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Heatsinks - active

Active heatsinks incorporate fans or other electric cooling device that requires power to run. This provides constant and more efficient air flow.

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Heatsinks – Thermal interface materials

To have the best possible transfer of the heat from the device to the heatsink some type of thermal interface material is placed between those two. It’s typically a ceramic, alumina or silver-based grease but it can also be in the form of a special pad or even a type of double-stick tape.

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Liquid cooling - Heatpipes

Heatpipe is a heat transfer device able to transport considerable amount of heat energy between two interfaces.

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Heatpipe - hermetically sealed tube with a fine wick structure lining the inner walls, hollow core in the center. Vacum inside, partialy filled with a special fluid.

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Heatpipe - hermetically sealed tube with a fine wick structure lining the inner walls, hollow core in the center. Vacum inside, partialy filled with a special fluid.

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Liquid cooling – Water cooling

Water cooling – circulating water over the processor or other components, therby keeping them cool. It’s one of the most efficient types of cooling, but expensive and very troublesome to use and maintain.

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Thermally advantaged chassis

Thermally advantaged chassis improve cooling for the processor by maintaining a temperature of 38°C or less at the processor heatsink inlet.

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Thermally advantaged chassis

To meet the requirements of the therm. ad. chassis, the following specifications are recommended:

• Accepts an industry-standard ATX, MicroATX or FlexATX motherboard• Accepts an industry-standard ATX, SFX or TFX power supply with integral exhaust fan• Uses a removable side cover with an adjustable processor duct and adapter card vent• Provides a primary chassis rear exhaust fan of 92mm or larger and an optional front-mounted 80mm fan (excluding any fans in the power supply).

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Processor duct

Processor duct – a tube positioned directly over the processor heatsink, allowing it to pull cool air from outside the chassis. The Processor duct is the most important part of the thermally advantaged chassis

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Processor duct

Processor duct’s effects can be viewed in the table. Tests where performed in a 25° C room and the following components were used:

-3GHz Pentium 4-D865PERL motherboard-GeForce 4 video card-DDR400 memory-Hard drive-CD-ROM drive-Sound card-Rear and front fan

Without CPU Duct

With CPU Duct

CPU inlet temp. 35° C 28° C

CPU fan speed 4050 rpm 2810 rpm

Sound level 39.8 Dba 29.9 Dba

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Conclusion

Upgrading a computer system to run faster is usually called overclocking. When chips run faster, they run hotter, so cooling upgrades go hand-in-hand with overclocking.

Systems that run cool tend to be more stable and more reliable, so even if you don’t overclock your system, ensuring that it runs cool is essential for trouble-free operation.

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damian kardański overclocking and cooling 1. framework 1.introduction 2.quartz crystals in...

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