The power supply below is similar in design and construction as the one showed earlier in the tutorial but it's of much higher quality (although the other one really isn't too bad) and has more features. The other power supply had essentially no features.
Multiple/Adjustable Fans:
This supply has 2 fans instead of one. Using multiple fans allows the same amount of air to be moved at much lower RPMs which results in quieter operation. When/if more air flow is needed (when the power supply is under more demand or when the internal case temperature is higher), the fans can increase in speed and keep the internal power supply components from overheating.
Fans Controls:
This fan has several ways to control the fan speed. It can allow the motherboard to influence fan speed. It can control the fan speed based on internal temperatures and there is a fan speed control on the rear of the fan.
Current Ratings:
The current ratings are simply the maximum current draw that the power supply can sustain.
Multiple Rail Voltage Regulators:
On most power supplies, there is only one voltage regulator. The supply looks at ONE of the output voltages and maintains that voltage within a specified range. All of the other output voltages are at the mercy of that one regulator. Better quality supplies provide dedicated regulators for 2 or more rail voltages. On older supplies, the 5 volt rails was the only regulated output. Now, you're seeing more power supplies that include a dedicated regulator for the 12 volt rails also.
Note:
All of the power supplies that I've shown you in this tutorial were essentially new. They had not yet had time to accumulate dust on the air intake. In time, dust will accumulate on the air intake grill. When this happens, it will prevent the power supply from cooling and will possibly lead to premature failure. If you open your computer case and the intake of the power supply is dusty, I recommend that you carefully vacuum it (with the computer unplugged - not simply off). Be sure not to pull any wires loose and don't put undue stress on any components mounted to the motherboard (or any other board). I don't, however, recommend vacuuming the circuit boards with a household vacuum. The brush fibers can get under some components and pull them loose. Also, a standard vacuum isn't static resistant. Some of the plastics used could create static charges that could destroy some board mounted components.
Universal Power Cable:
Most personal computers use a universal power cable. It's also used on many other types of electronic equipment. I'm sure that everyone's probably seen cable but for those who haven't...
Power Supplies with Monitor Connections:
The power supply below has a second connector. This connector used to be on virtually all power supplies but you rarely see them now. They are used to power a monitor. There is a special cable that connects between the monitor and the supply. The monitor will only receive power when the power supply is on.
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