Power
supply
Choosing a power supply can be a daunting task.
Looking at the total output (in watts) is not enough. A
PC's power supply unit transfer electricity to components
in your PC through three different lines - we usually call
them rails. These rails are the 3.3 volt, 5 volt and 12
volt rails. Electricity from the 12 volt rail is usually
used for hard drives and CD/DVD-ROMs, the 5 volt rail is
used to supply power to the processor and the 3.3 volt rail
is used to power add-on and integrated components. However,
there are some exceptions. Athlon 64 and Pentium 4 use an
additional ATX 12 volt cable, drawing extra electricity
from the 12 volt rail to help power the processor. Some
high-end graphics card also comes equipped with an
additional power connector, so they can also draw
electricity from the 12 volt rail.Needless to say, you power supply must be able to supply the electricity requested by all components inside your PC. Failure to do so mean your PC may experience system crashes and instabilities. You could check whether or not your power supply is supplying enough power by monitoring the voltage values of each rail through the BIOS or by using hardware monitoring software. If a rail's value drops or exceeds 10 % of the specified value (3.3, 5 and 12 volts), your power supply is barely coping with the load. As an example, this can be a value of 10,9 (or below) volt or 13,1 volt (or above) on your power supply 12 volt rails.
Fortunately, picking a good power supply (or one that's good enough) is not that hard. First, look at the technical specification of the power supply. They usually put some info on the box or a sticker on the power supply itself. The total output should be no less than 350 watts. Second, you need to look at the watts per rail, you can get the watts by multiplying the ampere values with the volt values (20 A x 12 volt equals 240 watts). You would want the 5 and 12 volt rails to have at least 150 watts. Remember, in most cases what you see in the technical specification is the maximum output, we need the sustained output. Make allowances and subtract 10 to 15 percent to get the estimated sustained output.
An extra tip is to never connect your monitor's power cable to your PC's power supply. Connect them directly to the UPS if available. The monitor will be an additional burden on your power supply, especially when they're just turning on.
Some power supply comes with S-ATA power connectors, silent mode and additional short circuit protection. While these are good features, they came at a price. For those of you with limited funds, choose a power supply that meets your PC's requirements electrically and still fits your budget. If you have additional funds, then you can choose the more feature packed version. Personally, I'd rather spend the fund to get a small, reliable, good UPS.
As you can see, a good power supply is a necessity for any PC. But the best power supply can only do so much, you got to have a clean input electricity to it as well. Most people still think that using a voltage regulator or stabilizer is enough. I think this is the bare minimum. To ensure your PC's health and data safety, use an uninterruptible power supply unit (UPS) with an automatic voltage regulator. Not only will this ensure your PC will get clean and stable electricity, they will also provide you with some additional time when you experience a blackout / brownout.
Remember that some parts of the world use a 110 volt standard while others use 220 volts. The actual volts itself may vary, for example some countries use a range between 220 and 240 volts, while others may use 200 to 220 volts. Make sure you have configured your UPS and power supply correctly before plugging them to your wall's electric socket.
Casing
Of course, for the most part you will be using a case to store all these components. There are many form factors to choose from desktop, mini-tower to full tower enclosures. They also vary in the number of 5.25' slots, metal used and additional features. While you may want the best looking case around, there are important factors to remember when choosing a case.
Airflow and Heat
Issues
Since the case is actually a container, usually box
shaped, air flow becomes an important factor to consider.
Without good airflow, heat will build up and temperature
will rise inside the case. Your PC's components can only
tolerate so much heat, so when the temperature is too much
it may become unstable or worse, permanently damaged.Even the coolest components will always generate heat, warming the air around it. That's why all cases come with some ventilation holes so that the hot air inside can be replaced by the cool air outside. If you remember your Physics 101, hot air tend to rise upwards, while cooler air tend to stay near the surface. That's why ventilation holes are place both in the bottom front and upper back area of the case. There may be additional holes in the side, but that's about it.
While the hot air will eventually go outside the case, we might want to speed things up a bit with some fans. Two well placed fans will do much to help airflow and keep the temperature from rising. One for the intake on the bottom front and another for the ??? on the upper back of the case.
Form
and Build
Remember that the form also determines how much room
inside the case. A bigger case can be used to store more
components, but more importantly it also means there is
more room for air. A mini-tower case is ideal for most
users, since they feature several 5.25' drive slots and a
single 3.5', room for three to five expansion slots.A mini-tower case is also usually lighter than a full tower case. Usually, since the case material (aluminum or steel) will also factor in its weight. Aluminum cases are lighter than steel cases, at the same form factor. Steel is much tougher though, so check for any creaks and moving parts in the case. A good case should not creak or move a budge.
Ergonomy and features
Just like the motherboard, the case is actually
comprised of several parts. Check how easy or difficult it
is to install hard drives and floppy. Some cases can also
be opened with using any tools, needless to say this
greatly simplifies troubleshooting and installation. The
side panel and other removable parts should also fit
without you using much force. Some cases may feature a
removable back panel for the motherboard, this makes the
installation process easier, since you can mount the
motherboard on this panel outside the case.Having a front panel for USB, Firewire and audio ports is a plus. With it, you don't have to reach for the back of the case when you want to use them. Those with security concerns will want a locking mechanism so not everyone can open the case.
Fan and Heatsinks
Of the many components and parts inside every PC, the processor, graphics card and hard drive are usually the ones that generates much heat. The faster they are, the higher the heat. So, we can't just rely on airflow to cool them down. That's why fan and heatsinks are usually bundled with the processor and graphics card.Some graphics card and motherboards come only with heatsinks, relying solely on good airflow. This method of cooling is known as passive cooling and is usually used when the components being cooled are already cool enough for the most part and these heatsinks are usually used as a precautionary measure. The advantage of this method is silence. If the component is quite hot, the heatsink can be quite large.
Since not every component can use large, passive heatsinks, some will use fans to directly cool the heatsink. This method is known as active cooling. Of course, the faster air blows on the heatsink, the cooler it gets. But very fast fans makes a lot of noise and not very suitable for everyday use. You can use larger, slower fans instead - they push relatively the same amount of air without having to spin very fast. On very hot processors and graphics card, you may see a combination of both large heatsink and fan, offering the best of both approaches.
Usually, heatsinks are made of aluminum. This metal quickly dissipates heat, so it's very ideal for heatsinks. There are also others made of copper, since copper absorbs heat much faster than aluminum. Some will even use both, using copper as the heatsink's base and aluminum for the fins, thus combining the advantages of both metals.
Heatsink design have also progress very far in the last couple of years. It's not that strange anymore to see heatsinks using both aluminum and copper in a variety of shapes and sizes. Manufacturers have also made use of heatpipes, using a pipe containing heat sensitive liquid to transfer heat much more quickly between parts of a heatsink. For most people, the heatsink bundled with your processor will be enough. Intel have been bundling heatsinks with their processor since the Pentium, with AMD following suit since the Athlon XP. So, always buy the official box packaged version when you're buying processors. The heatsink bundled inside is tested and guaranteed to work with your processor.
For hard drives, you can get hard drive enclosures equipped with a fan to cool them down. A more direct and less expensive approach will be to place another fan just for the hard drives and let the air through from in front of the casing. Not only will this cool the hard drives, but they will also help airflow since the case have additional holes for intake air.
Another important factor to remember is the room temperature. Since we're relying on the air to keep things cool, we have to cool the air in the room where we're going to use our PC. The best fan / heatsink and casing can not cool any component if the air is already too hot. So keep the room temperature around 25 to 30 degrees Celsius.
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