The system is almost complete. The power supply serves as the beating heart of the computer, driving voltage (and wattage) to all operating devices. Most modern mid- and full-tower cases will mount the PSU in the bottom of the case, though some still run top-mounted PSUs. Small Form Factor (SFF) and mini-ITX cases have unique space constraints that sometimes make for creative PSU location. Generally, though, it’s a bottom mount.
There are three classifications of power supplies:
- Fully Modular: All cables can be disconnected and removed from the PSU, including the 24-pin and 8-pin cables.
- Semi-Modular: All cables except the 24-pin and 8-pin/EPS cables can be removed from the PSU.
- Non-Modular: No cables can be removed, and all are connected directly into the PSU housing. This means that unused cables become excess and must be hidden. Non-modular PSUs tend to be a little bit more affordable as a result.
How to Install a PSU
Step 1 – Determine the location of the PSU
Locate the PSU mounting point within the case. If the case has a PSU shroud, there’s also a good chance that a PSU bracket is included – the bracket is installed to the PSU prior to its mounting in the system, and serves to make the process easier. Shrouds will also conceal the cables – a major benefit, and one which the NZXT S340 and NZXT H440 leverage for cleaner cable management. Hiding the cables behind a PSU shroud also means that it’s difficult to make connections once the unit is installed. To this end, we’d recommend connecting all necessary cables to the power supply (if it is modular) prior to installation.
To determine which cables are needed, have a look over your components.
These are the common requirements of a power supply:
- 24-pin cable for the motherboard (always needed)
- 4/8-pin EPS12V cable for the motherboard, near the CPU (always needed)
- 6/8-pin PCI-e cable for video cards (often needed, but not always; sometimes multiple are required)
- SATA power cable for SATA-attached SSDs (sometimes required – but not for PCI-e/M.2 SSDs)
- MOLEX 4-pin cable for fans and accessories (sometimes required)
Next, figure out how many of each cable you’ll need. Systems with multiple video cards or SSDs/HDDs may need additional cables connected, whereas less complex machines can get away with a minimalistic approach to cables.
Attach those that will be necessary. Don’t connect them just yet – we’ll do that next.
Step 2 – Determine the orientation of the PSU
Now, once the mounting location is found and cables readied, determine the orientation of the PSU. Most bottom-mounted cases will offer ventilation on the underside of the case, generally including a dust filter for preventative maintenance. In these cases, install the PSU with the fan facing down (so that it can breathe – especially important to pay attention to when working with shrouds).
In cases that are top-mounted or with unique mounting locations, check the manual. Generally, the preferred orientation is one which will expose the fan to the outside air for fresh intake. If that is not possible or if the PSU doesn’t butt-up against a side panel, install the power supply with the fan facing down. This is sub-optimal as it will intake warmed air that’s being exhausted through the CPU’s fans (if not using liquid), but is sometimes necessary.
Step 3 – Mount the PSU
Finally, hold the PSU in its final resting position and begin the process of screwing-in the four accompanying screws. These are hex-head Phillips screws (you can also use a hex driver). There should be four installed, in most builds. – Steve Burke, GamersNexus