Your computer's case isn't impenetrable, but it generally protects your PC from most potential system-destroyers, including spilled liquids, dust, and curious children. Unfortunately, your system produces vast quantities of heat—its own worst enemy. In fact, a computer's CPU generates so much heat that if it runs for even a few seconds without dissipating heat through a cooling device, such as a heatsink or waterblock, the processor will destroy itself. And to make matters worse, your computer case, defending the system against outside threats, traps the heat inside. Custom system builders have a variety of cooling devices at their disposal, including heatsinks and watercooling units, but most rely on case fans and heatsink fans, which suck out the heat and breathe fresh air into your simmering system.
Case fans may not cool the entire chassis evenly, however, especially if you overclock certain components or if tangled cables disrupt the system's airflow. If you believe heat is threatening your computer's precious guts, you'll need to pinpoint any dangerous hot air pockets, which means you'll need a temperature gauge that measures not just your PC's overall temp, but the temperature in specific locations. Enter the removable, multiple-sensor temperature gauge, a device that just might save your PC.
 Time To Fill Another Drive Bay
If you search online retailers for PC temperature gauges, you'll find out that many gauges have the same basic characteristics: flat or bulbous sensors; small, black-and-white LCDs (liquid-crystal displays); external buttons or dials; and 5.25-inch wide bodies that slide snugly into one of your case's free optical drive bays. To lure users otherwise unwilling to sacrifice a drive bay, some manufacturers add hard drive mounts and fans. The drive sits just behind the device's front panel. Some new temperature gauges even have USB (Universal Serial Bus) and FireWire ports.
The LCD displays the thermal sensor's temperature reading. Some devices have a small display that sits next to the buttons or knobs that let you customize the temperature gauge. Other temperature gauges trade control buttons and features for multiple displays. Some cases also often have a built-in LCD and single temperature sensor. If you're handy with a Dremel and want to measure only one location's temperature, you can save drive bay space by adding a small, single-sensor, LCD-only temperature gauge. Many temperature gauges display sensor readings in degrees Celsius, but users who prefer Fahrenheit can configure some high-end gauges to display in Fahrenheit. |
Use bulb sensors to check your case's temp, and slide flat sensors into tight spaces.
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Temperature gauges that have few sensors and options are inexpensive, but they generally lack two important features that make high-end gauges attractive to heat-and-noise-conscious users: high temperature alerts and fan control.
Most fans spin at a single, preset speed whether the system is idle or under a full load. If you aren't having heat-related problems and want to reduce your system's fan noise, you can use a high-end temperature gauge that includes a rheobus to lower fan speeds. This type of temperature gauge has several fan connectors and potentiometers that let you adjust the voltage flowing to individual fans. When you lower the fan's voltage, the fan slows down. Thanks to the control feature, you can lower your fans while your system is idle and crank them back up when your system takes on heavy loads. The Fan Commander 7-Channel Fan Controller, for example, includes dials that let you manually control individual fan speeds.
Some gauges can automatically control fans based on preset temperature values. By letting the gauge automatically adjust the settings, you can ensure that all of your system's fans are on when you stress your computer. Although some controllers don't let you adjust fan speeds, they can power off individual fans and then power them on again when their related sensors register unacceptable temperatures, which means you can fire up a game or other intensive software without manually adjusting your fans. By turning off unneeded fans, such controllers reduce your system's noise.
Multisensor temperature gauges generally have two types of diodes: bulb and flat. Although both sensors are fragile, the bulb diode is the hardier of the two. You can suspend a bulb sensor inside the case to monitor the ambient temperature, or you can use thermal tape to attach it to a flat surface, such as a chipset or hard drive. However, the bulb's shape means you can't place it in particularly tight locations, such as the gap between a heatsink and a processor. Flat sensors easily attach to flat surfaces and fit into the small gaps bulb sensors can't reach, but these sensors are very fragile. You can easily break a flat sensor by bending it or bumping it into an object. |
Some temperature gauges, such as this Enermax UC-A8FATR4, can let you adjust fan speeds to lower your PC's noise.
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Don't Put This Under Your Tongue
Determine which locations you plan to monitor and what bulb types you'll need before you buy a temperature gauge, as the number and type of sensor varies from gauge to gauge. For example, one model may have six bulb sensors and two flat sensors but another may have six flat sensors and two bulb sensors.
If you're not sure where to place your temperature gauge's sensors, aim for three of your system's hottest components: the hard drive, the processor, and the motherboard chipset. You may also want to monitor your system's ambient temperature to make sure your system maintains a consistent airflow. A representative from AMD suggested to us suspending a bulb sensor in front of the heatsink fan to monitor the temperature of the air flowing toward the heatsink. |
If you have an Intel-based motherboard, you can use the Windows-friendly Intel Active Monitor to keep tabs on the processor's temp.
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You can attach either type of diode to a hard drive by running thermal tape over it. Some manufacturers suggest particular locations that let the sensor accurately read the drive's temperature. Seagate, for example, recommends placing the sensor near the drive's back end (opposite the power and data connectors) of its Barracuda-series drives. If you're not sure where to place the sensor, check your drive's manual. Motherboard chipsets generally sport heatsinks or heatsink/fan combos, which means you'll have trouble attaching either type of diode directly to the core top of the chipset.
Placing a sensor near your CPU is tricky. You can't put the sensor directly on the core because it will block the heatsink from contacting the entire core surface. As a result, processors generally don't make great candidates for external sensors. AMD's old Athlon XP processor line makes for an exception, however. Athlon XP processors have a raised core and four small pads that create a gap between the heatsink and the body of the processor. AMD's representative told us that a user should be able to slide a flat sensor into the gap without trouble. If you place a sensor in this gap, keep in mind that although the sensor itself is flat, its cable is not. If you wedge the cable under the heatsink, you may break the heatsink's contact with the processor's core.
On the other hand, AMD's Athlon 64 and newer processors have a small case that covers the top of the processor, including the processor core. As a result, these processors (and Intel P4 processors that have similar designs) don't have the gap that Athlon XP's offer. You can approximate the CPU's temp by placing the sensor in between the heatsink's fins. Once you slip the sensor in between the fins, angle it downward to push it as close to the bottom center of the heatsink as possible.
If you're short on drive bays or simply don't want to buy a temperature gauge, you can check your processor's temperature in your system's BIOS (Basic Input/Output System). Most processors have on-die diodes that work with the motherboard to calculate the processor's temperature. You can view this temperature in the PC Health section of your BIOS, but your system won't be running under a full load. If you want to check the on-die diode temp readings from Windows, you'll need to install a third-party application. Some motherboard applications have overclocking software that displays processor temps, and Intel offers Active Monitor, which is a free utility that uses the on-die diode to report your processor's temperature. You can run it at any time, which means you can keep an eye on the processor's temp while stressing your system. 
by Joshua Gulick
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Pushing The Limit
So, how hot is too hot? Our sister publication, CPU, reviews heatsinks. Its reviewers find that standard systems using today's components (including the stock, processor manufacturer-provided heatsinks) often run with an internal temperature in the neighborhood of 52 degrees Celsius. (The room temperature in CPU's testing lab is about 23 degrees Celsius). However, we've seen systems run stable even into the mid-60's. If you suspect heat is an issue for your computer, put another computer in the same room and then test its temperature. If the two systems have wildly different temperatures in the same environment, your problem PC likely owes its woes to excessive heat inside the case.
Individual hard drive families have different temps. If you don't have your drive's manual, you can generally find the drive's max temp by visiting the manufacturer's Web site and browsing the drive's specifications. |
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