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Keep Your Computer Cool - in Any Season

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Keep Your Computer Cool - in Any Season

In the Northern Hemisphere, August is the month which puts your computer's (and your own) ability to tolerate outside heat to the test. Scorching 90-degree plus days have reached from Maine to Florida, and over most of the Midwest and Plains states. And, since computer cooling depends upon pulling outside air through your system, hot days make it a little harder to achieve this goal.

Although the heat outdoors gets all the attention, even after Fall replaces Summer, the heat inside your computer is a far bigger enemy to your system and your data than the hottest outside day ever was.

Heat Sources Inside Your Computer

Whether it's a scorching summer day or a frigid winter night, the inside of your computer scarcely notices once you flip the power switch. Virtually all computers have a fan built into the power supply, which creates a negative vacuum to pull air through your system for cooling; however, that single fan can be easily overwhelmed by all the heat sources found in today's "hot" PCs, including:

  • The processor
  • The memory modules
  • The chipset
  • The drives
  • The video card's chipset and memory

Fortunately, some of these components already have an on-board fan to help keep things cool:

  • The processor's fan is usually powered from a 3-pin motherboard-based fan jack (the 3rd wire allows hardware-monitoring features in your motherboard to monitor the fan's RPMs, possibly alerting you if the fan slows down or isn't spinning properly). Less sophisticated setups use a pass-through power cable which connects to a spare Molex drive power connector instead. Unfortunately this precludes any RPM monitoring.
  • Mid-range and high-end videocards often use a heatsink and fan to cool the chipset
  • Most cases have at least one or two additional fans to help cool the interior

However, standard fans aren't always enough, especially if you are using the fastest systems or if you're planning to do a bit of overclocking.

What are the benefits of improved system cooling?

  • Longer component life
  • Greater reliability and stability, fewer lockups and other problems
  • The ability to tolerate upgrades without problems

Bringing Down the Heat

When looking to give your system some aid in cooling itself, start by targeting often neglected hot spots. How can you determine these hot spots? According to leading overclocking-oriented Web sites, some areas of your computer you might not have considered include:

  • the motherboard chipset
  • the drive bays
  • expansion slots

What if you aren't interested in overclocking your system? Even stock systems benefit from running cooler, especially as systems running over 1GHz become increasingly common.

The Motherboard Chipset

Think the processor is the only hot chip on your motherboard? Think again. The North Bridge or Memory Controller Hub (MCH) chip (which provides high-speed interfacing between the processor, memory, and PCI devices, can get hot enough to burn your finger, and the heat it throws off means more heat inside your computer. The latest chipsets from Intel, AMD, VIA, Ali, and SiS, are smaller than their predecessors and yet run at ever-higher clock speeds.

To fight heat buildup in the chipset, add chipset coolers. Two of the leading vendors in this emerging field are Vantec USA www.vantecusa.com and TennMax www.tennmax.com. Vantec USA's kit features both active (fan-based) and passive heatsinks that can be used to cool the North Bridge or Memory Controller Hub, South Bridge or I/O Controller Hub, as well as video card chipsets, while TennMax's chipset cooler can also be adapted to popular video cards.

In most cases even a passive cooler (one with no fan) will make a big difference in cooling the chipset. Most of these are basically the same passive heat sinks that used to be used on older 386 and 486 processors (which were about the same size and heat output as modern chipsets), now finding a new life cooling chipsets instead. Most of these use a simple peel and stick installation that makes them easy to use.

Video Card Chipset Coolers

Video card-specific coolers are much more numerous, and are frequently added as replacements for both passive heatsinks and lower-performance active heatsinks that many video card makers provide for their mid-range and high-end 3D accelerators. If faster game performance is your goal, add-on video card chipset coolers enable you to successfully use overclocking utilities to increase the performance of your video card

When you look at video card chipset coolers, keep in mind that the fans on the most effective models are usually large enough that the adjacent PCI slot is blocked, so that you effectively lose a slot. If you need every slot in your system, look for coolers that use thin fans that allow enough room for a card in the next slot.

Compatibility Issues to Watch For

Unlike processor coolers, which are designed in close cooperation with processor socket and slot designs, chipset coolers for both motherboard and video card chipsets are sometimes much harder to install. While some of the latest motherboard and video card products provide standardized locations for mounting pins, others don't. Some coolers are larger than others, and may not be able to fit safely next to bulky electronic components on some motherboards and video cards. Look for a peel and stick installation as an easy method to avoid problems. The only drawback is that once they are stuck on, they can be difficult to pry off later (not that you'd ever need to remove them), and if you do take them off, you'll have to find a replacement double sided thermal tape to reinstall.

Read reviews carefully and check the Web sites of the best-performing products to see if your particular video card model or motherboard model has been tested with a particular cooler model.

Drive Bay Coolers

Users of high-performance 10,000 RPM and 15,000 RPM hard drives from companies such as Seagate were the first people to realize that high performance drives were also running hot. The first drive bay coolers were marketed especially to users of these drives.

While most PC users prefer the less-expensive 7,200 rpm drives, these drives also run hotter than previous models. Add to that the widespread popularity of CD-RW drives. With their powerful lasers, and drive subsystems these devices are increasingly in need of dedicated cooling systems. Overclocking review sources provide reviews for drive bay coolers, but you should note that most require that you sacrifice a drive bay to make room for the cooler. And, some poorly-designed drive bay coolers don't cool very well, leaving a draft in your wallet where your money used to be but with little benefit otherwise. For reliable cooling products, see PC Power and Cooling www.pcpowerandcooling.com for several choices in drive and drive bay coolers.

Better Cooling for Your Processor

There are two ways to buy replacement processors:

  • Retail-boxed products with a manufacturer direct 3-year warranty; these include a high quality active fan heatsink selected by the CPU manufacturer
  • OEM (bulk-packed) with no warranty from the CPU manufacturer, and probably only a 30-day warranty from the company you purchase it from; these come with no heat sink, in that case the heatsink choice is up to you

Boxed processors universally include very high quality heat sinks that are designed to withstand the worst system environments. They have to be good, as the processor manufacturer provides a long warranty and can't be sure how good the cooling is in the system in which it will be installed, so they shoot on the side of overkill. As such a boxed processor is always a safe bet.

OEM processors on the other hand, require that you select a heat sink that can adequately cool the device in the system in which you install it. If you are into extreme overclocking, you can find high-end heat sinks which are better than those provided on the boxed processors, but you'll have to spend a little more money to get something that good. Depending upon the vendor, you can buy your processor and heatsink separately, or buy them as a bundle with a motherboard (which may get you a longer warranty than the normal 30-day return policy for OEM processors).

One problem that has been cropping up recently with processor heat sinks relates to the tension of the clips, which are used to attach them to the CPU socket. AMD in particular originally specified too high a tension for their processors, which has resulted in a rash of cracked CPU chips! Make sure your the heat sink you are using is designed to apply no more than about 20 lbs. of static force on the CPU, if you have to press down with more weight than that to install the clips, you risk damaging the processor.

I think that some of the best heat sinks on the market right now are the Arcticooler models from Agilent Technologies (Hewlett-Packard's chip division). You can find out more about them at
http://www.agilent.com/view/thermal/.

There is also a short document which explains them at
http://www.agilent.com/Feature/English/archive/E011.html.

The Arcticoolers are a patented heat sink design, and several companies are now producing similar models under license, or are otherwise copying their design. Generally, however, the originals are of superior construction and design to the copies, and they have the engineering data and expertise to back them up. The fans are high quality (ball bearing motors), the clips have the correct tension, and they are designed to fit within the prescribed keep-out areas so they fit all ATX motherboard/chassis combinations. The version for Pentium III and Athlon processors is the HACA-0001, otherwise called Arcticooler Model CA. You can purchase them from most electronics supply companies like Newark Electronics
http://www.newark.com.

With an OEM processor, you can attach any heatsink compatible with your processor and motherboard. As with other coolers, be sure to check compatibility carefully. Changes in the design of Socket 370 and Socket A processors in particular can literally lead to processor damage if an incorrect heatsink is attached, or the incorrect tension or offset clips are used. Be sure to verify that your particular CPU speed and model matches the design of the heatsink you want.

Cables Vs Coolers - Coolers Need Help to Win

One of the biggest problems for any type of add-on cooling is the presence of wide ribbon cables for IDE, SCSI, and floppy drives. These cables frequently create air dams, areas of nearly-stagnant air inside the case, even when auxiliary fans are used.

Cooling-conscious users with very careful hands discovered that they could slit the insulation between the wires on drive ribbon cables and band the individual wires into small round bundles, permitting much better airflow through the system. If you're more likely to cut yourself with an Xacto knife than cut the cable correctly, so-called "rounded cables" can be purchased from many vendors. See the overclocking web sites listed at the end of the article for details and pricing.

If spending money on expensive rounded cables isn't your cup of tea, though, you can do just fine by your system by merely being conscious of your existing cable routing. If you carefully route and fold your ribbon cables instead of wadding and stuffing them into the chassis, the rounded cables are probably not necessary.

Thermal Transfer - Paste or Tape?

There are two methods you can use to assure better heat transfer between either passive or active heatsinks and chips:

  • Thermal paste
  • Thermal tape

Of these two, thermal paste has been recommended for years, and with good reason. If a positive-locking mechanism is available to attach a heatsink to a chip, thermal paste fills the inescapable small gaps between metal surfaces and provides excellent heat transfer.

What about thermal tape? Thermal tape, as the name implies, provides better heat transfer than metal-to-metal contact, but tests reveal that it doesn't do nearly as good a job as thermal paste. Thermal tape is best reserved for situations in which a heat sink can't be attached to a chip with a mechanical lock (such as a clamp or locking pins), but must be attached with thermal tape only (it's double-stick). Thermal tape will dry out over time: some users have had processors with taped-on heatsinks fail because the tape adhesive dried out and the processor no longer had a good contact with the heatsink.

Which Metal Provides the Best Heat Transfer?

There are two major types of metal used to make heatsinks:

  • aluminum
  • copper

Until recently, aluminum was used almost exclusively because it combines light weight (to avoid damaging a motherboard through excessive weight) and good heat transfer. However, the advent of greater than 1GHz processors (which run hotter than slower processors) has caused copper to become an increasingly popular choice for high-performance heatsinks. Unfortunately, copper heatsinks are more expensive than aluminum, but, more critically, are a lot heavier. Some copper heatsinks for the AMD Socket A (Athlon / Duron) processors exceed AMD's 300-gram recommended weight limit for Socket A's 462-pin design. Ship a system with one of these overweight heatsinks installed and you might wind up with a ruined motherboard when it arrives.

Intel's hottest processor, the Pentium 4 with its 423-pin socket, has moved the recommended mounting location for the heatsink from the socket itself to the case wall beneath the motherboard. Almost all Socket 423 motherboards and Pentium 4-compatible cases have four holes around the socket and corresponding holes in the case wall to support heavy copper-based active heatsinks. As an alternative for users who don't want to trade in their perfectly good Pentium II and Pentium III cases, some vendors provide reinforcing plates to fit between the motherboard and the case to bear the weight.

Keeping An Eye on Internal Temperatures

There are various ways to avoid "frying" the interior of your system. Many recent systems have a BIOS option that monitors processor temperature and fan RPMs; this information can be viewed when you boot the system, and can also be reported to system-monitoring programs.

PC Power and Cooling www.pcpowercooling.com sells the 110-Alarm, a small device powered by an extra drive power connector. It sounds an alarm if the temperature inside the case exceeds 110 degrees Fahrenheit.

The following Web sites provide news, reviews, and online shopping for the cooling components discussed in this review:

You can also find information on cooling issues at

For some of the best technical discussions of system cooling, check out the Form Factors Web site at

http://www.formfactors.org/developer/specs/atx/atxspecs.htm

In particular, download and read the two documents concerning cooling titled "Performance ATX Desktop System Thermal Design Suggestions v1.0" and "ATX Thermal Design Suggestions 1.0". These show you what it takes to professionally engineer proper cooling for your system.

No matter what the season, your computer needs to be properly designed to stay cool!

Copyright©2002 Pearson Education. All rights reserved.

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