The computer power supply is the life of a computer as it’s the one that powers it up. The computer power supply just doesn’t get any respect and its job is one of the most important of any component for your computer’s longevity and performance. It’s one of the most important part to consider in building your own computer from scratch.
Specifically the computer power supply’s job is to convert the AC power supplied by your home into nice clean DC power for your computer.
What the Computer Power Supply Really Does
The computer power supply’s main job is to supply three different DC (direct current) voltages to the computer. These voltages are as follows.
- +12VDC for motors and voltage regulators, newer processors
+5VDC for motherboard, voltage regulators, serial & parallel ports, PCI & AGP ports
+3.3VDC for the motherboard chipset, system memory, PCI & AGP cards
The computer power supply also regulates current and helps to cool the computer with its intake and exhaust fans. The direct current supplied by the power supply must also be free of noise, spikes and dips in voltage (brownouts).
Don’t Buy a Cheap Computer Power Supply
A good computer power supply will run a series of checks before it allows the motherboard to turn on. If everything is ok it sends what is called a Power Good signal to the motherboard. Once the motherboard has received this signal it knows it is okay to boot up.
Cheap power supplies may not perform their internal checks before sending the all clear signal for the motherboard to power up. This can cause damage to the motherboard or other components in the computer because the proper voltages are not present at startup.
Hopefully this has convinced you not to trust the cheap power supply that often comes with a case.
Quick Guide for Computer Power Supply Wattage
Here’s a quick guide to determine the total average wattage of the different components the power supply will be supplying power for. Do the math and then add a 100 watts (just to be safe) and you’ve got an idea (ball park) of the total wattage needed for your computer.
- Motherboard-, 15-30 watts
- Low-End CPU-, 20-30 watts
- Mid To High-End CPU-, 40-100 watts
- RAM-, 7 watts per 128 MB
- PCI Add-In Card-, 5 watts
- Low To Mid-Range Graphics-, 20-60 watts
- High-End Graphics-, 60-100 watts
- IDE Hard Drive-, 10-30 watts
- Optical Drives-, 10-25 watts
ATX Connector
The computer power supply is connected to the motherboard by a big white 20 pin connector. Recently this connector was changed from a 20 pin to a 24 pin. The new designation is the ATX 2.0 connector. Make sure you know which connector (20 or 24) is on your motherboard before buying a computer power supply. Also, be aware that PCI Express videocards have a connector that is not common on older PSUs (power supply units).
Cooling
All computer power supplys require some form of onboard cooling due to the heat they generate. The best type of onboard fan to have is a 12cm(diameter). These larger fans can push more air at slower speeds which results in less noise. This is a good thing. Smaller fans must spin faster to generate the same air flow and that leads to more noise.
Detachable Cables
Older computer power supplies had a certain number of power leads that emerge from the rear of the PSU. If you could use them all great, if not you had to find somewhere to tuck them. The newer computer power supplies have modular power cables that permit you to just use the power cables that you need. This is a good thing because it reduces clutter inside the computer case, which in turn increases the cooling efficiency of the fans.
Conclusion
Don’t settle for a low quality power supply. Make sure you buy a quality computer power supply that is large enough to meet the computer’s power requirements and that it has the right power connectors to fit the motherboard that you have picked out.
If you are using a SATA drive or running dual video cards (Crossfire or SLI) be sure your selection has the right connectors and the wattage needed to run your configuration.
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