CIS 1110A - Computer Operating Systems and Maintenance
This lesson discusses heat, power, and troubleshooting.
Objectives important to this lesson:
Cooling components that produce heat
Selecting an adequate power supply
Troubleshooting boot problems, power problems, and other
The chapter opens with basic advice about keeping a computer cool
enough to work. In the author's discussion, "cool" is a relative
term. It would be nice to keep the components of a computer cool
enough to touch, but cool enough to work
is the usual goal. Like a car engine, it is expected to
get hot when it runs. Like the engine, if the computer gets too
hot, you are not going anywhere.
Keep the case closed when the computer is running -
a well designed case has an intended flow of air across heat
producing components; an open case does not produce the intended
flow of air; opening the case may allow immediate cooling if the
air intakes have been blocked, but it defeats the fans; if
someone has blocked the intake vents, correct that
Keep the computer clean - dust, pet hair, and more
will be pulled into the computer by its fans, so clean it
regularly In the video below, our friend Linus gives good advice
and decent comedy:
Move the computer - what were you thinking
when you put a dripping pot of flowers over your computer? did
it need a bath?; don't put electronic devices where they will
get hot, wet, dusty, kicked, or knocked over.
We have already mentioned cooling devices for
processors, which can be as simple as a set of metal fins that act
as radiators for the processor, and as complicated as a fan that
comes on at a certain temperature and runs faster at higher
temperatures. Make sure you apply good thermal paste between the
processor chip and the heat
dissipation plate that mounts on the CPU. Fans for computer
cases, for graphics cards, and for RAM modules can be similarly
complicated. In the image below, you see a dashboard for my
computer that presents current temperatures and volts being used..
Liquid cooling systems are more elaborate. Click
the link in the last paragraph to read a good, short article from
Intel about the difference between air and liquid cooling systems.
Note that the liquid systems often include a cooling fan for the
liquid being used, making them similar to a car's cooling system.
More expensive systems may use refrigeration units outside the
On page 168, the text turns to considerations about choosing a
The first one is that it has to fit the
case in which you will install it. Look for one that is sized
for your chosen case (ATX or Micro-ATX).
Next, we need to know the total number of
watts the computer will need (figure the sum of the watts for
all components, then add more for expansion). The text mentions
that common power supply values are around 500 W, 850 W, and
1000 W. When you calculate the total load, remember to estimate
the load your USB devices are likely to require.
To calculate the correct total, the text reminds us of the
formula for Watts: Watts = Volts x
You should also consider the power available in each circuit
(also called a rail) coming from
the power supply. Our author calls our attention to the positive
12-volt circuit coming from the motherboard. She mentions
that we need to consider the number of watts available
on this rail. It is commonly used to connect power to the
motherboard, but note the chart on page 168 that shows the same
rail may be used for SATA power. On the next page, the author
tells us that a video card is likely to use power from this rail
as well. If we have components in the computer that will draw
more watts on any rail than an otherwise adequate power supply
can provide, we need to select a different power supply with
more power on that rail. The author proposes that you allow for
an additional 30% above your calculated
Power supplies often have a variety of connectors,
some of which will not be used. This is good, since you often
upgrade or add devices. It is possible that you will run out of
power connectors of a particular type, so be careful to get a
power supply that either has enough connectors of the right kind
or enough that you can adapt to be the right kind if you are
putting in a lot of options. Note the image on page 169 of an
adapter that turns two Molex connectors into one PCIe 6-pin
connector. In the image below you see three adapters to go from
Molex power connectors to a device that expects a SATA
The author becomes a little confusing, telling us that all
(internal) power supplies have fans, then
noting that some do not. There are few generalizations about
computers that have no exceptions. More fans are better, but
noisier. Do you want the dumb computer cool, or don't you?
Power supplies sold to customers in the US usually have a
large switch select either 110 (115) or 220
volt connection. Select the right voltage for your situation,
and the right power yoke (cord) to run from the computer to your
Using multiple video cards typically
requires support from the power supply. NVIDIA
cards require SLI support, and AMD
cards require Crossfire support. Get a power
supply that supports the cards you intend to use.
The author switches to the topic of troubleshooting on page 171.
On that page, you see a very general flow chart which is not much
help in actual troubleshooting, but the concept is worth
considering. Here is a short version.
Question the user having the problem.
Back up data (if possible).
Examine the system and ask questions based on what you find.
List your guesses about the cause of the problem. (You can
come back to this step, or any other.)
Test your most likely theory. If you are right, fix the
computer. If not, test another theory, get help, or give up.
Our author lists more steps about documentation and proactively
avoiding future problems. I will suggest that you should start
taking notes when you start talking to the user or reading a
trouble report. Write down what you do or you can't say later what
it was that worked or failed.
On the next page, the author suggests several sources of help,
which everyone eventually needs.
search the web for solutions
talk/type to people you know, people on technical chat
services, people on forums about the products in question, and
people who do support for the products
if possible, use diagnostic software from vendors and
read the furnished manual, either in paper form or as a
ask a technical friend to look at the problem: another set of
eyes may see what yours missed
The text spends the next ten pages expanding on each step in the
author's investigative plan. The remainder of the chapter is a
series of articles about troubleshooting various subsystems of
computers. You should read through that section before trying to
do this week's assignments. As an added attraction, I suggest
watching the video provided below from JayzTwoCents (Jason
And for those who need another video, and may be tired of Linus,
here is one from Jay about using a water cooled system, except
that he chose to use beer instead of water. I think he actually
proves that drinking and tech work are not a good mix. If you are
going to drink, don't work on a computer. Enjoy.
Read the chapter, and the next one for next week.
Complete the assignments and class discussion made in
this module, which are due by 6pm next week.