Building a Computer for A+ Study Part VII: The Case and Power Supply

Part seven in a series on the basics of building a computer to prepare for the A+ certification exams.

Computer Case

A computer case is the enclosure that contains most of the components of a computer. Computer cases are also referred to as the chassis, system unit, or tower. Computer cases can come in many different sizes, shapes and colors as well as be made from different materials such as aluminum, steel, or plastic. The size and shape of a computer case is usually determined by the form factor of the motherboard.

When buying a computer case, it is important to remember that the motherboard generally determines the overall size of the case as well as which parts you can put into it. The form factor of a motherboard dictates the specifications of the computer case you choose: physical dimensions, type of power supply, and location of mounting holes. It is important to remember that the motherboard also has to properly fit into the computer case that you choose.

Power Supply

Your computer needs power. A lot of computer cases come with a power supply unit but if the one you choose does not, you will have to purchase one separately. Most basic computers are fine with a 250 to 300 watt power supply unit. However, if you plan on adding more demanding graphic cards, multiple hard disks drives or other internal components, you may want to get a more powerful power supply unit. Just make sure that you choose one that not only physically fits in your computer case but one that is also appropriate for the form factor of the motherboard.
A power supply unit, also simply referred to as a PSU, is offered in modular and non-modular models. Modular PSUs include detachable cables, which allow you to use only the ones you need. This means less annoying cable tangles and a much cleaner look inside the computer case. While modular PSUs tend to be more expensive, the payoff is less clutter and better air circulation throughout the case. The more common non-modular PSU has all the cables connected to the power supply.
Power supply units have several different types of connectors that plug into your internal components for power:
  • P1 Power Connector (20- or 24- pin connector for motherboard)
  • CPU Power Connector (8-pin for high-end CPUs)
  • Molex Connector (older hard disk drives & optical disk drives as well as some high-end graphic cards)
  • Mini Connector (floppy disk drives)
  • SATA Connector (newer hard disk drives & optical disk drives)
  • PCI Express Power Connector (8-pin connector for high-end graphic cards)

When choosing a PSU, don’t be cheap. A good PSU will deliver stable and clean power. Look for affordability without sacrificing quality and the potential for future upgrades. Furthermore, when you’re choosing a PSU, look beyond the total output (e.g. 500 watts) and make sure it has a combined +12 Volt continuous current rating of 24 Amps or greater. If you are having trouble deciding what type of PSU you need, there are online power supply calculators that will give you a general idea on what to consider while selecting a power supply for the computer you are building (or upgrading).

What I picked

For the case, I choose the In-Win Z589T Black Steel MicroATX Mini Tower Computer Case. This case comes with a 350 watts power supply unit. The front I/O panel provides access to two USB 2.0 and two audio ports. The case has bays for two external 5.25″ drives, an internal 3.5″ drive and two external 3.5″ bays. More importantly, this particular case has a screwless design for drive bays and expansion slots for convenient, quick installation of components without any type of screwdriver.

Even though the computer case that I chose came with a 350 watts PSU, I decided to swap it out with a Thermaltake TR2430W PSU. The PSU that comes with the case is decent but very basic. I usually prefer purchasing a more robust one than the stock models that come with some cases. The Thermaltake TR2430W not only is 430 watts but also includes industrial-grade power protections such as Over-Voltage Protection, Over Power Protection and Short-Circuit Protection.

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