WINMX Assorted Textfiles/Ebooks.tar/Text - Tech - None Like it Hot (Cooling your PC) (TXT).zip/None Like it Hot (Cooling your PC).txt

Text File | 2002-07-29 | 14KB | 263 lines

More on this page
http://www.informationweek.com/LP/columnists/langa/2001/06.htm

Fred Langa

None Like It Hot

Excessive heat is a CPU's worst enemy. Here are software utilities that can
help.

Have you ever touched the surface of a working computerÆs CPU chip --- say,
a Pentium or an Athlon? These days, they get hot enough to take off your
fingerprints.

Fortunately, it's not that easy to touch the surface of a working central
processing unit: Almost all CPUs are covered with heat-sink-and-fan
assemblies that help dump the chipÆs heat into the air inside your
computerÆs case, from which itÆs vented out by one or more additional fans.

You see, heat is the enemy of a CPU chip. The cooler a CPU chip is kept,
the more stable it is and the longer it lasts û itÆs as simple as that. At
abnormally high temperatures, a CPU may behave erratically or lock up; if
youÆre lucky, normal operation will resume when things cool off. But a
single extreme temperature spike, or long, frequent periods of running
"outside thermal spec," can permanently damage or destroy a CPU.

Thermal management in personal computers --- and CPUs in particular ---used
to be a fairly forgiving science with a wide range of acceptable,
roughly-engineered solutions. Early PCs had one fan inside the power
supply, for example, to handle cooling for the entire system. But as CPUs
got faster and more advanced, they pumped more and more energy through
smaller and smaller wire traces at ever-increasing clock frequencies. The
result is that today, without properly-sized and functioning heat sinks and
fans, most CPUs would literally cook themselves to death in short order.

ThatÆs why so many current desktop PC designs internally resemble miniature
wind tunnels: The higher-end and faster your PC, the more fans itÆs likely
to have.

The 1.2GHz PC sitting at my feet, for instance, has no less than five fans
busily whirring away: a very large fan ventilating the case as a whole, a
smaller fan ventilating the power supply (and, to a lesser degree, the
case), a medium-sized fan blowing air down through the CPUÆs massive heat
sink, and a pair of tiny fan/heatsinks mounted on other chips --- one on
the video cardÆs graphics processor, and one on the motherboardÆs largest
chip.

Although the main focus of this article is desktop PCs, laptops also can
run hot, but usually not as hot as full-sized desktop units. That's because
laptops use special lower-voltage components and aggressive power-saving
technologies, and usually run at lower speeds than top-of-the-line desktop
models. Many laptops can get by with smaller fans, or even no fans at all
(as can some special desktop designs). One common trick laptops use is to
dissipate heat through the laptopÆs housing, using the metal case as a heat
sink --- often to the chagrin of travelers on long-duration plane flights,
who find their thighs getting singed by the excess heat pouring out through
the bottom of their laptop.

Problem Areas
While there are exceptions, most PCs from major vendors start their lives
reasonably well-ventilated and are able to keep the CPU chip and other
components within thermal specs --- as long as the fans keep turning and
the airflow remains unobstructed.

But many vendors use cheap fans with relatively short lives: If a fan dies
on you, your first warning might be a general and seemingly-inexplicable
system failure.

Or, if you donÆt clean the inside of your PC from time to time, the air
intakes may become clogged with dust, dirt and pet hair, leading to
overheating and trouble. (This will only sound weird to you if youÆve never
opened the case of a PC that has been allowed to run undisturbed and
uncleaned for a long time. The amount of crud that accumulates inside a PC
case can be truly amazing --- and disgusting!)

Some system vendors also have been known to cut corners, producing PCs that
are technically within thermal specs, but running far hotter than they need
to. This puts unnecessary stress on the system and all but ensures a
shorter system life.

And if you modified your system by adding a new component (say, a new CD
drive), your placement of cables and connectors could interfere with the
airflow, possibly causing localized overheating.

A bit further afield, if you built your own system from scratch or replaced
the CPU, it could be hard to know if you chose the right combination of
fans and heatsinks.

So the question is this: How can you tell if your system is properly
cooled? How can you tell if the airflow is right for your PC? How can you
tell (without opening the case) that all the fans are turning? How can you
tell that your PC isnÆt susceptible to erratic operation or even premature
death caused by too-high or barely in-spec temperatures?

Learning From The Overclockers
"Overclockers" are people who push their CPUs to speeds way beyond their
rated capacity. In fact, overclockers often compete among themselves to see
who can run a given chip the fastest --- the PC hardware equivalent of
automotive hot rodding.

In running their chips far out of spec, overclockers face major thermal
problems: The loss of CPU cooling for even a second or two (!) can totally
fry a highly-overclocked chip beyond recovery. As a result, the overclocker
community has developed many heat monitoring and management tools and
techniques.

With today's hot-running standard chips, many major-brand system vendors
have adopted some of the overclockersÆ tools and techniques to help cope
with thermal issues in their off-the-shelf, higher-end systems. For
example, many of todayÆs motherboards (maybe yours!) now come with built-in
sensors to keep track of things like fan speed, and system and CPU
temperatures. Sometimes, the sensors are tied to a basic alarm: If the
system gets too hot, an alarm sounds. Other more sophisticated systems
allow direct reading of this information through either the BIOS setup
program, or via special software. But this software is almost never
included as part of the base system. Even if your system has these advanced
sensors built in, you may not know that they're there, or be able to access
the information they can provide.

But there's a ton of software on the Web, if you know where to look. Some
of this software is specific to one brand or type of motherboard; other
programs support many brands and models. For a taste of whatÆs available
--- much of it free, thanks to the overclocker community (bless 'em) ---
poke around in Tweakfiles.

I've tried some of that software myself. For example:

Motherboard and CPU Monitors
Perhaps the best-known and most widely-used freeware thermal monitoring
tool is called simply Motherboard Monitor (or MBM).  When you run it on a
PC equipped with the appropriate thermal and fan sensors, it will show you
the information it collects in the Windows system tray. It also can sound
alarms or launch corrective actions (e.g. shutting down) in the event it
detects an out-of-spec reading.

The MBM site will give you all the info you need, including whether or not
your system can use it. But it's not highly polished, and you can expect to
have to do some digging to find out what options you have.

(The MBM site is also a good place to find out the maximum recommended
temperatures for your particular CPU. If your specific brand, type and
model of CPU isn't listed there, you can try the HeatSink Guide, or go to
the home pages of your CPU vendor and search their technical literature.)

While MBM is good, IÆve come to prefer the look and feel of a slightly
different freeware tool called MBProbe. According to the site, it

"àmonitors voltages, temperatures and fan speeds using hardware monitoring
chip(s) available on many modern motherboards. Its features include:
Up to 9 voltage, 4 temperature and 3 fan speed readings (subject to the
limitations of hardware monitoring chip(s) present).
Automatic detection of monitoring chips.
Small memory footprint.
Setting of nominal voltage and fan speeds with warning thresholds.
Setting of temperature warning limits and offset readings.
Setting of sensor used for each temperature reading.
Temperature display in Celsius or Fahrenheit.
Customisable task when critical temperature is exceeded for more than 30
seconds continuously.
Ignores fan warnings for 10 seconds after system comes out of suspend.
Swappable temperature display in status icon on taskbar.
Event and history logs."
I have it running in my system tray. The display alternates between showing
my CPU temperature and the motherboard temperature, and I have it set to
sound an alarm if the temperatures, voltages, or fan speeds drift outside
safe ranges.

Like MBM, MBProbe is a little awkward to set up correctly. But once itÆs
running, itÆs unobtrusive and kinda cool. Right now, for example, I know
that my CPU and motherboard fans are both spinning within a few RPM of
their rated speeds; the motherboard is well-cooled and running just a
couple degrees above room temperature; the CPU also is well-cooled, running
almost 60 degrees C (or about 100 degrees F) below its rated "safe maximum"
temperature; and the power supply is delivering nominal voltages.

If I stress my PC --- say, if I start a long download while burning a CD
and also doing routine office tasks --- IÆll see the CPU and motherboard
temperatures climb modestly, although never even remotely close to danger
levels. (Another sign of good cooling.) WhatÆs more, when the workload goes
down, the CPU temperature falls almost immediately, which also is an
indication that my systemÆs heatsink, fans and airflow are all properly
sized and working as they should.

So this simple kind of system monitoring can show you very quickly whether
your system has a serious thermal problem or not. And beyond that basic,
initial OK/Not-OK assessment, I also feel better knowing that the software
is keeping an eye on things on an ongoing basis. If a fan dies, or the
airflow becomes obstructed, or if my power supply starts to drift out of
spec, IÆll know about it and can take action before any damage can occur.

If ItÆs Not OK: Cooling Options
My system was OK. But what if you should find that your system isnÆt OK?

First, open the case and look for dead fans or airflow blockages (dust,
poorly-routed cables, etc.). If those arenÆt the problem, then your
fan/heatsink combination may not be OK. A source like TomÆs Hardware Guide
can lead you to a world of custom hardware-oriented cooling solutions.

But there also are 100 percent software solutions for CPU cooling. Some
operating systems (including Windows 2000) have this software solution
built in, but Win9x does not. The cooling trick is the use of an HLT (or
"halt") instruction during idle times. Stopping the CPU instead of letting
it idle at full speed helps keep temperatures down.

And by "idle times" I donÆt mean when the PC goes to sleep. Consider that,
when youÆre typing, a quarter second might pass between consecutive
keystrokes. If you have a 500 MHz processor, that means that from one
keystroke to the next, your CPU twiddles its thumbs for 125 million cycles
(even more for faster processors). If many or most of those cycles can be
shut off, your CPU will stay cooler.

Of course, thereÆs more going on inside any PC than just waiting for
keystrokes, and the more multitasking thatÆs going on, the fewer idle
cycles there are for a CPU-cooler app to work on. Results vary widely,
depending on how you use your PC, but the theory is sound: The more idle
cycles there are, the more an HLT command can help.

(Interesting side note: A CPU that's HLT-ed also saves power, so this
approach has energy saving benefits that can be useful on a desktop, and
very significant on a battery-powered laptop.)

You can find many free and low-cost CPU cooler software utilities via any
search engine, such as this Google search.

But here are some of the more well-known ones:

CpuIdle  (trialware: $20 if registered)
WinCooler (freeware)
Rain (freeware)
Waterfall (freeware)
Waterfall Pro 2.1 (trialware; $25)
And there are more reviewed and rated at Benchtest.Com

Diminishing Returns
ThereÆs a ton of evidence that CPU coolers help a lot on systems that run
hot, but I didnÆt know what IÆd see on my system because MBProbe had
already shown that my CPU is extremely well-cooled to start with. And in
fact, none of the cooler software I tried produced any noticeable results
at all.

But I took this as a sign of success, not failure: With my systemÆs
already-excellent mechanical cooling (via airflow) there just wasnÆt much
left for these software-only coolers to do. It was further proof that the
engineers who designed my system did their homework well.

With that reassurance, I uninstalled the CPU cooler tools, but left MBProbe
running. ItÆs a permanent addition to my system tray to help make sure that
my system stays thermally healthy for what I hope will be a long life.

No Surprises
In a perfect world, weÆd never have to think about heat issues in PCs: All
vendors would design their systems well, fans would never die, dust would
never choke off a systemÆs airflow, and everything would work perfectly.

IÆm not holding my breath waiting for that perfect day. Instead, IÆll run a
small, free monitoring tool to keep an eye on whatÆs going on inside my PC,
and if I need to, take steps via software or hardware to correct any
problems that arise.

What about you? What monitoring or cooling tools have you tried? What
results have you gotten? What heat-related problems have you seen?