Power Supplies (PSU)

Category overview

The power supply is the part of the build that, if it fails, can take other components with it. Picking a unit with the right wattage, efficiency and quality avoids both immediate stability problems and longer-term reliability issues.

What this category covers

ATX and SFX power supplies for desktop and small form factor builds, server PSUs in 1U and 2U form factors, and redundant power supply units for servers and workstations that need continuous operation through a single PSU (Power Supply Unit) failure.

How to choose a power supply

Size by actual draw plus headroom

Add the rated power of the CPU and GPU under load, then add roughly 30 percent for drives, fans, motherboard and headroom. PSUs are most efficient and last longest when running at around 50 percent of their rated wattage. Going much larger than needed wastes money but is not harmful; going too small causes stability and noise problems.

Pick the right efficiency rating

80 PLUS Bronze is the entry level for office systems. Gold is the sweet spot for most builds, balancing cost and efficiency. Platinum and Titanium make sense for systems that run constantly under load, where the electricity savings add up over time.

Check the connectors

Modern high-power graphics cards may use a 12V-2x6 (the updated 12VHPWR) connector with ATX 3.x. Older cards use multiple 8-pin PCIe connectors. The PSU has to provide the right connectors natively, not through risky adapters.

Choose modular or non-modular

Fully modular PSUs let unused cables stay out of the case for cleaner airflow and easier builds. Semi-modular units leave only the essential cables fixed. Non-modular is fine for budget builds but always means more cabling to manage.

Key features to compare

Rail design

Modern PSUs are typically single-rail on the 12 V side, which simplifies high-current loads. Multi-rail designs split the 12 V into several protected groups; this is more relevant for server builds and certified industrial equipment.

Build quality and protections

Look for over-current, over-voltage, over-temperature, short-circuit and over-power protection in the specifications. Independent reviews of the specific model are the best reference for actual build quality.

Cable length

For larger cases or front-mounted PSUs, longer cables matter. Most ATX cables are sized for mid-tower cases by default; full-tower and unusual layouts may need extension cables.

What to check before buying

• What is the actual peak power draw of the planned build?
• Does the PSU provide the right connectors natively for the GPU?
• Is ATX 3.x and 12V-2x6 support required for a current high-end GPU?
• Does the form factor match the case (ATX, SFX, SFX-L)?
• For redundant server PSUs: does the chassis support hot-swap and is the wattage matched per unit?

Frequently asked questions

How big a PSU do I really need?

For a typical office or productivity build with a mid-range CPU and integrated graphics, 450 to 550 W is comfortable. For a build with a discrete GPU, target the GPU manufacturer's recommended PSU wattage as a starting point. For high-end gaming and workstation builds with current top-tier GPUs, 850 to 1200 W is common.

Is more wattage always better?

No. A PSU that is much larger than the load runs at lower efficiency and is wasteful. A reasonable rule is to size so the typical workload runs the PSU at around 40 to 60 percent load, which is also the peak efficiency range for most units.

What does 80 PLUS Gold actually mean?

The 80 PLUS rating measures power conversion efficiency at different loads. Gold guarantees at least 87 percent efficiency at 20 percent and 100 percent load, and 90 percent at 50 percent load. Higher tiers (Platinum, Titanium) raise these thresholds. A more efficient PSU produces less heat and uses less electricity for the same workload.

Should I buy an ATX 3.x power supply?

ATX 3.x specifies behaviour for transient power spikes from modern GPUs and includes the 12V-2x6 connector. For a build with a current high-end GPU, ATX 3.x is the safer choice. For budget builds with mid-range GPUs or integrated graphics, a quality ATX 2.x PSU is fine.

How long do power supplies last?

A good-quality PSU can run for 7 to 10 years with stable performance, often longer in lighter-load office systems. Failures are most common in the first weeks of use (initial defects) or much later as capacitors age. Heat and dust shorten that lifespan; clean cases with good airflow extend it.