A power supply unit converts the AC mains feed from the wall or PDU into the regulated low-voltage DC rails — principally 12V, with 5V and 3.3V derived from it — that the motherboard, CPUs, DIMMs, drives and fans actually run on. In a desktop that is a single sealed box; in a rack server it is usually a pair of hot-swap modules sharing the load, so the machine stays up when one fails. Everything listed here is a tested, graded unit intended either as a like-for-like replacement or as the second module that turns a single-PSU server into a redundant one.
At a glance
Typical deployments
Replacing a failed module
The most common reason to buy. Match the vendor part number rather than the wattage alone — firmware and connector keying differ between generations, and mixing ratings in the same chassis will often throw a PSU mismatch alert even when both modules work.
Adding redundancy to a single-PSU server
Plenty of servers ship with one module and an empty second bay. Fitting a matching unit and feeding it from a separate PDU or circuit removes a single point of failure for a fraction of the cost of a second server.
Populated or GPU-loaded chassis
Fully stocked DIMM slots, high-TDP processors and accelerator cards push 12V demand well past what an entry-level PSU can hold. Prioritise headroom here: size for peak draw with one module offline, not for typical idle load.
Low-draw and edge nodes
A lightly configured 1U firewall, file or backup node rarely needs a high-wattage supply. A smaller unit running nearer its efficient band wastes less energy and produces less fan noise than an oversized one loafing at 15 per cent load.
Desktops and workstations
For a PC or workstation the job is simpler: confirm the physical standard and cabling the case expects, then leave margin above the combined CPU and graphics requirement so the supply is not running flat out under sustained load.
Cold spares and fleet maintenance
If you run several identical hosts, a shelf spare per platform turns a PSU failure into a five-minute swap rather than a procurement exercise. Buying the same part number across the fleet keeps that spare universally useful.
Why buy from CompuWyze
- Every unit load tested and verified before it leaves us, not simply powered on
- 12-month return-to-base warranty covering hardware faults and failures
- Honest Grade A and Grade B condition grading, so you know what arrives
- Wattage, part number and connector type listed on each product page
- Stock across Dell PowerEdge, HP ProLiant and Lenovo ThinkSystem platforms
- Compatibility advice from people who work with this hardware daily — ask before you order
Frequently asked questions
What does the power supply do in a computer?
It takes single-phase AC from the mains and converts it to the stable DC voltages the components need, chiefly a 12V rail that feeds the processors, memory subsystem and expansion cards. It also handles inrush at power-on, filters mains noise, and signals the board when its outputs are within tolerance. If a PSU degrades, the symptoms are often mistaken for memory or motherboard faults — random resets, failures under load, or a machine that will not post at all.
What server PSUs do you stock?
Hot-swap redundant power supplies across a range of wattages — typically 460W, 750W, 800W and 1400W — compatible with Dell PowerEdge, HP ProLiant and Lenovo ThinkSystem rack servers. Wattage and connector type are clearly listed on each product page.
Are server PSUs interchangeable between brands?
In most cases, no — server PSUs use proprietary connectors and firmware specific to each vendor's platform. Always match the PSU to your specific server model. If you're unsure, our team can advise on compatibility before you order.
What does refurbished mean here?
Units are pulled from decommissioned enterprise hardware, cleaned, inspected and then tested under load rather than just briefly energised. They are graded A or B: Grade A is cosmetically excellent, Grade B carries light wear such as rack marks or minor scuffs. Grade has no bearing on electrical testing — both are held to the same functional standard.
Are they suitable for production use?
Yes. Enterprise PSUs are built for continuous duty and are among the most straightforward parts of a server to test conclusively. Where a machine takes two modules, the sensible approach is a matched pair on separate power feeds, which means a single unit failing is an alert rather than an outage.
How much wattage do I need?
Work from your actual configuration — processor TDP, number of populated DIMM slots, drive count and any PCIe cards or accelerators — and then check what the chassis supports. In a redundant pair, size so that one module alone can carry peak draw. Bear in mind that most servers will only accept the wattage options their vendor validated for that generation, so the choice is usually narrower than it first appears.
Do refurbished power supplies come with a warranty?
Yes — all units carry a 12-month return-to-base warranty covering hardware faults and failures.