CIS 1110A - Computer Operating Systems and Maintenance

Module 4

This lesson discusses heat, power, and troubleshooting. Objectives important to this lesson:

  1. Cooling components that produce heat
  2. Selecting an adequate power supply
  3. Troubleshooting methods
  4. Troubleshooting boot problems, power problems, and other related problems
  5. Current assignments


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..

Temp and power data

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 computer case.

On page 168, the text turns to considerations about choosing a power supply.

  • 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 Amps
  • 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 total.
  • 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 power connector.
    Molex to SATA power adapter
  • 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 wall socket.
  • 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.

  1. Question the user having the problem.
  2. Back up data (if possible).
  3. Examine the system and ask questions based on what you find.
  4. List your guesses about the cause of the problem. (You can come back to this step, or any other.)
  5. 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 manufacturers
  • read the furnished manual, either in paper form or as a download
  • 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 Langevin).

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.


  1. Read the chapter, and the next one for next week.
  2. Complete the assignments and class discussion made in this module, which are due by 6pm next week.