Power Supply Units

Power supplies for servers, workstations and desktops — hot-plug server units from HPE, HP, Dell and Lenovo, ATX and SFX units from Corsair, ASUS and LC-Power, and DC supplies for network hardware.

Buying guide ↓

Replacing a server supply is a different job from buying a desktop one

Enterprise power supplies are not generic. An HPE 800 W hot-plug unit fits the server families it was designed for and nothing else — the chassis, the backplane connector and the firmware handshake all have to match. Order by the manufacturer part number printed on the failed unit (P38997-B21, 865414-B21, 503296-B21 and so on), not by wattage. Two supplies of the same wattage from the same vendor are frequently not interchangeable.

Desktop and workstation supplies are the opposite: ATX is a standard, and any compliant unit of adequate wattage will fit a standard case.

Form factor comes before wattage

ATX is the full-size standard and fits most tower cases. SFX and SFX-L are the small-form-factor sizes for compact builds — SFX-L is slightly longer and takes a bigger, quieter fan. 1U and other rack formats are server-specific. A supply that is physically too long will not clear the drive cage no matter how good it is, so confirm the case takes the form factor first and choose wattage second.

Wattage, and the headroom worth having

Add up the processor and graphics card draw, allow for drives and fans, then leave margin. A supply running at around half its rated output sits in its most efficient band and its fan stays slow, which is why specifying somewhat above the calculated figure is sensible rather than wasteful. Modern graphics cards also draw brief spikes well above their nominal rating, and an underspecified supply shows this as a machine that reboots under load rather than one that fails outright.

Efficiency ratings

80 PLUS Gold and Platinum certifications describe how much mains power reaches the components rather than becoming heat. Higher grades cost more and return it slowly through the electricity bill — the better argument for them in a workstation is that less waste heat means a quieter machine and a cooler room.

Modular cabling

A fully modular supply lets you fit only the cables the build needs. In a small case this is the difference between tidy airflow and a bundle of unused leads stuffed behind the drive cage.

Network and appliance supplies

The PLANET and NETGEAR units here are DC supplies for switches, media converters and industrial gear rather than computer power supplies. They are matched to specific equipment by voltage and connector — check the device's requirement rather than substituting on wattage alone.

Brands

HPE, HP, Dell, Lenovo and Synology for servers and appliances; Corsair, ASUS and LC-Power for ATX and SFX; PLANET and NETGEAR for network hardware.

Trade pricing and business accounts are available for UK organisations, and bulk orders are welcome — request a quote.