Power supplies are tricky. If the budget for your custom-built PC is limited, you can save a pretty penny by choosing a low-voltage power supply--but in doing so you limit your upgrade options.
Enermax NAXN ENP450AST ($45)
If you’re assembling a budget machine, I suggest installing the Enermax NAXN ENP450AST. As the device’s model number implies, this product is a 450W power supply, so it’s comfortably capable of running a fairly heavy-duty system--one equipped with several hard drives as well as a lower-end graphics card.
This power supply holds a pair of 12V power rails. Most of the more substantial components inside your computer will draw power from a 12V rail; the graphics card is the most notable example. Multiple 12V power rails have become increasingly common in recent years, and having more than one in a power supply offers you a little more flexibility.
Cooler Master Silent Pro RSA00-AMBAJ3-US ($159)
For a gaming-oriented PC, I like to use parts that leave a lot of room to grow. The 1000W Cooler Master Silent Pro fits that description, offering a nice balance between features and price.
I recommend this power supply for a specific reason: It's modular. Since its cables are detachable, you connect only the ones you need. That flexibility can go a long way toward preventing internal cable clutter, and it makes working inside the chassis that much easier. Even if you open the case only once or twice over the life of your PC, do yourself a favor and be sure to get a modular power supply.
Certified as 80 Plus Bronze, the Silent Pro is at least 82 percent power efficient. That means you can expect roughly 800 of the 1000 watts it draws to feed directly into your PC, so they aren’t wasted. The 80 Plus certification system is designed to promote energy efficiency and conservation, and can help you keep a lid on your utility bill. Efficient power supplies are generally quieter, too, carrying large fans (like the one on this model) that circulate air while keeping the decibels low. And the Silent Pro is SLI Ready, meaning it was built with SLI and CrossFire graphics in mind and will deliver enough power to run two Nvidia or AMD graphics cards in tandem.