Cooling: Troubleshoot Overheating PC Problems C 25/1. Prevent Serious System Crashes Caused by Your PC Overheating and Prolong Your PC s Life

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1 Cooling: Troubleshoot Overheating PC Problems C 25/1 Prevent Serious System Crashes Caused by Your PC Overheating and Prolong Your PC s Life With the information in this article you can: Prevent your PC from crashing due to an overheated processor Boost Windows performance with correct cooling Maximise your processor s life by stopping it from overheating All computers generate heat when they are running. As PCs become more and more powerful, ever-greater temperatures are produced. Your computer will already be equipped with components to dissipate this heat, but are they really up to the job? An overheating processor can cause your PC to crash without warning, and without any indication of what caused the error. If you are experiencing mysterious PC crashes, where the computer just turns itself off or re-boots without warning, then it is highly likely that this can be fixed by repairing your PC s cooling system. Once you have read this article, you will be able to confidently replace or upgrade the case fans in your PC. You will also find out how to optimise the airflow through a computer case. Once you have used the included figures to identify exactly how your PC is cooled, you will be able to make informed decisions about the number, type, location and flow-direction of any additional fans you may need. Dr Steve North: PC cooling can be a somewhat controversial subject. The beginner will often hear widely differing opinions about the best cooling equipment to use and the ideal place to position it. This article will tell you how heat may be affecting your PC s performance and what you can do about it. Identify problems caused by an overheating PC... C 25/2 Trace the cause of an overheating processor... C 25/2 The essential components to keep your PC cool... C 25/4 Choosing the right case fan for your PC... C 25/5 Correctly installing a new fan inside your PC... C 25/8 1

2 C 25/2 Cooling: Troubleshoot Overheating PC Problems!? PC components that move and conduct electricity will generate heat. Identify Problems Caused by an Overheating PC The components in your PC can get very hot. If your PC s processor starts overheating, it can very often lead to all kinds of crashes in Windows. Your PC may switch itself off or re-boot without displaying an error message. An overheating PC will suffer from degraded performance, meaning that Windows runs slower than it should. If these are the kind of problems that are plaguing you, it is essential that you improve your PC s cooling. A computer generates heat in three main areas: the CPU (Central Processing Unit) or processor, the hard drive and the power supply unit. These are the components in a PC that experience the greatest levels of physical movement (the rotating platters in the hard drive, for example) and the greatest concentrations of electrical activity. In the latter case, the CPU has very small currents moving rapidly through the multiple pathways of a microchip. The power supply unit has much larger currents passing through a tightly wound metal coil. Before considering methods to improve your PC s cooling, it is necessary to clean your PC, as dust inside its case can be a major factor in overheating problems.!? You should regularly clean the inside of your computer. Trace the Cause of an Overheating Processor Even a slight rise in temperature may cause your computer to malfunction. It doesn t matter how many fans you have fitted, if the airflow through your PC is obstructed the temperature can rise and cause a processor malfunction. At regular intervals, it is important to clean the dust from the inside of your computer case. This should be done very gently, to avoid any damage to sensitive components. You will need the following items: 2

3 Cooling: Troubleshoot Overheating PC Problems C 25/3 A small Phillips screwdriver. A can of compressed air for cleaning computers (if available). If not, a very soft bristled, small paintbrush. Do not touch the circuit boards in your computer unless you are touching a well-earthed metal object. This is not just for your safety; even small amounts of static electricity can ruin sensitive microchips. Remember that mains electricity is dangerous and you should proceed with great care. To get started cleaning the inside of your computer: 1. Shutdown Windows and turn OFF any power button on the front panel of your PC. 2. If fitted, turn the small (usually black) rocker switch on the PC s back panel from 1 to If the PC is plugged into a domestic mains socket with a switch, turn it off (but leave the plug in the socket to use its earth connection). If the socket does not have a switch, unplug the plug from the socket. 4. Open your PC s case. 5. While touching the internal components of your PC, you need to keep your hand on a well-earthed object. If your PC mains plug was removed from the wall at step 3, then your PC chassis is no longer earthed. You will need to touch an alternative earth, such as an unpainted water pipe. If the mains plug is still in the wall socket, you can keep you hand on an unpainted part of your PC s chassis. Avoid shuffling your feet, as this can generate static build-up. 6. Very gently (using the compressed air or paintbrush) remove all the loose dust from inside the computer case. Clean the fans, the CPU s heatsink, the power supply unit, the hard drive and the circuit boards. Pay particular attention to ensuring that any ventilation holes are free from blockage. 7. Replace the computer s case.! Take precautions when opening your PC s case. Keep yourself earthed to avoid static electricity damaging your PC. 3

4 C 25/4 Cooling: Troubleshoot Overheating PC Problems 8. Plug your PC back into the mains socket (if removed earlier) and switch the socket on. 9. If fitted, turn the small rocker switch on the PC s back panel from 0 to Turn ON any power button on the front panel of your PC.!? The Essential Components to Keep Your PC Cool In the first section of this article, we looked at how heat is generated inside a computer. It was also explained that dust could exacerbate the situation. Now we will look at the essential components in your PC used to reduce the temperature inside a PC. Computer cooling is achieved using fans, a heatsink and filtered ventilation holes. The devices used to keep your PC cool Power supply unit fans cannot usually be replaced without changing the entire device. 4 The above diagram illustrates the following cooling components: The power supply unit fan this is usually built into the unit. It may be mounted vertically (as shown above), or sometimes may be found lying horizontally inside the chassis of the power supply unit. If this fan fails,

5 Cooling: Troubleshoot Overheating PC Problems C 25/5 you will almost certainly have to replace the entire component. This is the primary fan fitted to almost all PCs, irrespective of their additional cooling arrangements. The CPU heatsink this is a metal-finned device that dissipates heat away from the processor. There is very little that can go wrong with a heatsink. One of the less common problems is a failure of its bonding to the CPU. This will require careful re-adhesion, as per the manufacturer s instructions. Be aware that even slight detachment of the heatsink from the processor may cause a relatively large increase in CPU temperature. The CPU fan originally, PCs were fitted with only a power supply unit fan and a CPU heatsink. As processor speeds increased, so did the heat generated. Most CPUs now have a fan fitted to the top of the heatsink. Some CPU fans may be replaced by unscrewing them from the CPU heatsink. If the fan is integral, then the entire CPU will have to be replaced. Additional fans most modern PCs have at least one additional (or secondary fan). This is commonly mounted in a bay below the power supply unit. However, some cases allow a choice of locations, including the front panel. These are occasionally referred to as drive fans, because some users install them to reduce the heat generated by a hard drive. Choosing the Right Case Fan for Your PC Replacing a PC fan will require you to open the case. Please follow the safety steps outlined earlier in this article (see page C 25/3) before you modify your PC s cooling hardware. Case fans for PCs come in various sizes (including 40mm, 60mm, 80mm, 92mm and 120mm), with two possible connector types. The most common size for a secondary case! The heatsink must be firmly attached to the CPU, or overheating may occur. Additional fans are also known as secondary fans or drive fans.!? 5

6 C 25/6 Cooling: Troubleshoot Overheating PC Problems Fans come in various sizes. 80mm is the most common. There are two types of fan connector. Some modern motherboards offer temperature monitoring. Look for a new fan that comes with a Molex to 4-pin adaptor. fan is 80mm x 80mm. If you are replacing a failed secondary fan, measure the existing unit so you know which size to buy. In addition, you will need to ascertain which connector type is used. The possible options are: 4-pin the same type of plug used to provide power to floppy disk drives. This will connect to the loom of power cables coming from the power supply unit. This is the traditional type of fan connector. 3-pin (or Molex) with this, the three wires are +12v, ground and a speed sensor feed that allows the PC to monitor and adjust (by varying the voltage) the fan s speed. This type of connector requires a spare plug (pins) of the appropriate type on the motherboard. It will only work with a modern motherboard that is equipped for this function. Refer to your motherboard manual for details of how to enable temperature monitoring. For a direct replacement fan, it is safest to buy a new component with the same connector. However, if you are adding an additional fan, you will need to find out if your motherboard has suitable Molex plugs. One useful tip is that you can buy replacement fans that come with a Molex to 4-pin adaptor. Alternatively, you can buy the adaptor as a separate item. This should cover most installation eventualities. Even if you are installing a new fan with a 4-pin connector, you must check that there is a spare 4-pin connector on your PC s power loom and that it will reach the new fan. Otherwise, you will find yourself having to buy an additional power extension/splitter lead. If your new fan is a direct replacement, it will be obvious where it should fit into the case. If you are fitting an extra fan, the position may require some consideration. When planning to add an additional fan, read the next section on correctly installing a new fan in your PC. When replacing a fan, always choose the largest size that the mounting point will allow. If you currently have an 80mm fan, but your 6

7 Cooling: Troubleshoot Overheating PC Problems C 25/7 mount will allow a 120mm fan, then it is a good idea to fit a fan of this size as it will allow for extra cooling. If the mount is limited to 80mm, it is even possible to purchase an 80mm to 120mm adaptor unit, allowing the larger fan to be used. Before deciding where in your PC case to position a new fan, it is important to look at the different size of drive bay that you will find in your PC. The bay size relates to the different size slots available at the top of your PC s case to add either floppy, CD-ROM or hard drives. If you are short on space inside your case it is common to add extra fans that fit inside an empty drive bay. The two different sizes are 5.25-inch and 3.5-inch inch bays are usually used to fit CD-ROM drives, while 3.5-inch are usually used for floppy drives. The bay widths are actually 4 inches (for the 3.5-inch drive) and 5.75 inches (for the 5.25-inch drive). The latter is known as half-height, because there used to be a full-height drive of the same width but double the height. Most modern tower PC cases will have three or four external 5.25-inch bays and two external 3.5-inch bays. There may also be an internal card cage that accommodates a number of additional 3.5-inch drives. You will also notice that (in typical British fashion!) drive bay sizes are measured Imperially and fans are measured Metrically. There are four possible locations for a secondary fan: Fan mounting points built into the case most modern cases provide two of these on the rear panel. They generally look like a fan grill with four screw holes for mounting. Occasionally, a case will have this type of mount on the front. Front mounted in a 5.25-inch (or half-height) drive bay this fits into a spare CD-ROM type drive bay. Front mounted in a 3.5-inch drive bay this fits into a spare floppy type drive bay. Always buy the largest replacement fan that your case will allow. A 3.5-inch drive bay is usually used to hold floppy drives. Secondary fans may be fitted in four different locations. You can use the existing mounting points, the drive bays or the internal card cage. 7

8 C 25/8 Cooling: Troubleshoot Overheating PC Problems Drive bay fans tend to be modules with several small fans. Internally mounted inside the 3.5-inch internal card cage. Fans that are fitted within drive bays tend to be units containing one or more fans, as opposed to the individual fans that are mounted directly on the case. Where multiple fans are included in one unit, the sizes will tend to be in the 40 60mm range.!? Yes No Test Power supply unit fans should blow air out. Additional rearmounted fans should also blow. Front-mounted fans should suck air into the case. Correctly Installing a New Fan Inside Your PC There is more to fitting a PC fan than just installing it in any available position. Depending on which way around it is orientated, a fan can either suck or blow. If a fan blows air into the case and over a heat-generating component (the power supply unit, for example), the CPU may become damagingly hot. This can lead to all kinds of Windows performance problems. If you only have one fan fitted (in the power supply unit), then this should definitely be blowing air out. This leaves the question, should an additional fan blow in or out? This depends on where it is located. If the secondary fan is on the rear panel, then it should also be exhausting warm air from the case. This acts to increase the volume and speed of air circulation. If you install the secondary fan in the sucking direction, then there is the danger that a local short circuit will occur in the airflow. The primary fan will actually be blowing out cold air that the secondary fan has just sucked in. That said, a secondary fan (or drive bay fan unit) mounted in the front of the case should be sucking in air. This is to match the air circulation through the front panel ventilation holes. If the frontmounted fan is blowing, then a partial vacuum will be created inside the case and temperatures may increase. In short, the desirable arrangement is to have air sucked in through the front of the case (through the ventilation holes 8

9 Cooling: Troubleshoot Overheating PC Problems C 25/9 and possibly an additional fan) and out through the back of the case (via the power supply unit fan and any additional rear-mounted fans). The following diagrams demonstrate the correct directions of air circulation with differing fan configurations: Primary power supply unit fan The air comes in through the front and out through the back. PC airflow circulation with a two-fan setup The above figure shows the correct direction of airflow where only a primary fan is fitted. The heat dissipated by the CPU fan and heatsink, is removed from the case by the rearmounted power supply unit fan. Cool air comes in through the ventilation holes to replace the warm air. You may also find that the ventilation holes at the front of the PC's case have a filter fitted behind them to remove dust and other air-borne particulates from being sucked into your PC's case and damaging components. From time to time, the amount of dust caught by this filter can prevent smooth airflow through your PC's case. It is therefore a good idea to periodically remove the filter, clean the dust from it and replace it. 9

10 C 25/10 Cooling: Troubleshoot Overheating PC Problems Primary power supply unit fan and rear-mounted secondary Fans that are located near to each other must pull air in the same direction (both sucking or both blowing). PC airflow circulation with a three-fan setup Unlike ventilation holes, front mounted fans are unfiltered. They may allow dust into the case. If a second fan is near to the power supply unit fan, it must also blow. If two fans installed next to each other blow in opposite directions, they will create an air short circuit. The second fan might even decrease overall airflow. If there are rear ventilation holes in your case and they are located next to the secondary fan, it can sometimes be helpful to cover them (with gaffer/duct tape, for example). Otherwise, you may find that the airflow short-circuits itself (in through the ventilation holes out through the nearby fan). Primary power supply unit fan and front-mounted secondary If the second fan is installed at the front of the case, then it should suck. If both fans are blowing out, then they would both try to create a vacuum inside the case, and there would be no real airflow. It should be noted that the front panel ventilation holes are usually filtered to prevent dust entering the case. If you use 10

11 Cooling: Troubleshoot Overheating PC Problems C 25/11 a front mounted fan to suck in air, you may introduce additional dust to the environment, then more frequent cleaning of the PC s internal components is likely to be required. PC airflow circulation with a three-fan setup Reversing the flow direction of a fan If you examine the blades of your fan, you will see that there is a curve in the surface of the blade. Each blade has a trailing and a leading edge. The concave side of the blade is designed to push (or scoop) the air. Therefore, the fan should rotate with this side first and the convex face following on behind. Most fans have an arrow to indicate its direction of rotation. Examining the blades should allow you to work out which way around the fan should be to suck, or to blow. If you install the fan and it is not delivering the desired result, simply take it out, turn it over and put it back in. You can add as many fans as are required, but keep to the air circulation rule (suck through the front and blow out of the back). Another useful rule of thumb is: suck cool air in You can identify which way a fan will push air, by examining the curvature of its blades. If a fan is not moving the airflow in the required direction, simply take if off and turn it around. 11

12 C 25/12 Cooling: Troubleshoot Overheating PC Problems at a low level and blow hot air out at a high level. This makes use of warm air s inclination to rise, creating a more powerful flow. Also when improving your PC s cooling, remember the following tips: Cable loom make sure that this is not obstructing the airflow over the CPU. Move it around, if necessary. This is especially important if your PC has thick IDE drive cables that can easily obstruct airflow. PCI cards (network interface or sound cards, for example) these may also generate heat. Where possible, try to leave empty slots between cards. This will both improve airflow and keep the ambient temperature low. Hard drive try to improve the airflow by leaving a space around this component This article has shown you how to remove any dust from inside your PC that might be causing overheating. Particularly important is unblocking the ventilation holes and any filters that may be fitted. You should now understand which parts of your PC get hot and how the CPU s heatsink and the case fans help to remove this heat. If a fan is malfunctioning, or you want to add an extra fan, you should be able to correctly plan an airflow route for your computer and get your PC well-ventilated and running at optimum performance. 12