How do you choose a compatible and reliable replacement power supply for a computer?

1 Check the wattage

The first thing you need to consider is how much power your computer needs and how much your current or potential PSU can provide. To do this, use online calculators or check the specifications of your components to estimate your power consumption. Generally, it's a good idea to have some headroom between your total wattage and your PSU's rated wattage in order to account for peak loads and efficiency losses. A good rule of thumb is to have at least 20% more wattage than your estimated power consumption. For example, if your computer needs 400 watts, you should look for a PSU with at least 480 watts.

2 Check the connectors

The next thing you need to check is whether your PSU has the right connectors for your motherboard and other devices. The most common connectors are the 24-pin ATX connector for the motherboard; the 4-pin or 8-pin EPS connector for the CPU; the 6-pin or 8-pin PCIe connector for the GPU; and the SATA or Molex connectors for the drives and fans. Make sure that your PSU has enough of each type of connector and that they match the ones on your components. You can also look for modular or semi-modular PSUs, which allow you to detach unused cables and reduce clutter.

3 Check the form factor

Another thing you need to check is whether your PSU fits in your case. The most common form factor for PSUs is ATX, which measures 150 x 86 x 140 mm (W x H x D). However, some cases may require smaller or larger PSUs, such as SFX, TFX or EPS. Check the dimensions of your case and your PSU, and make sure that they are compatible. Also, check the airflow and ventilation of your case, and choose a PSU with a suitable fan size and orientation.

4 Check the quality and reliability

The last thing you need to check is the quality and reliability of your PSU. A cheap or low-quality PSU can fail prematurely, produce unstable voltages, generate excessive heat and noise or even cause fires or explosions. In order to avoid this, look for the following: a PSU from a reputable brand, with a high-efficiency rating (such as 80 Plus Bronze, Silver, Gold, Platinum, or Titanium); with a long warranty period (at least three years); and with good reviews from users and experts. Avoid PSUs that are too old, refurbished or second-hand, as they may have degraded components or hidden defects.

5 Here’s what else to consider

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