How to Match a Replacement Server Power Supply by Part Number

Start with the label, not the wattage

Every server power supply carries at least two identifiers: the part number the server vendor assigned to it, and the model number of the manufacturer that actually built it — Delta, Liteon, Artesyn, Flex, and a few others. Order by the vendor part number. A "750W Dell power supply" is not a single part: the same wattage exists across generations with different connectors, firmware, and efficiency variants, and they are not interchangeable.

Where to look, by vendor:

• Dell: an alphanumeric part number on the label, usually printed with a leading zero. iDRAC also reports it under the hardware inventory.
• HPE: the label lists both an assembly number and a spare part number. Quote the spare number — that is what replacement stock is keyed to.
• Lenovo/IBM: use the FRU number, not the option number.
• Supermicro: the model number itself (PWS- prefix) is the orderable part.

Several part numbers are often interchangeable within one platform family, because a vendor may source the same output rating from two manufacturers. Once you have any one of them, you can search server power supplies by part number, and our sales team will confirm cross-compatible alternatives free of charge if the exact number is out of stock.

Wattage and efficiency tier

In a redundant pair, the replacement must match the surviving unit's wattage. Efficiency tier (80 PLUS Gold, Platinum, Titanium) matters more than most people expect: vendors typically assign different part numbers to different tiers at the same wattage, and some platforms treat them as distinct models. The safe order of preference: same part number first, then a vendor-listed equivalent at the same wattage and tier.

Upgrading wattage is legitimate only in specific cases — a single-PSU chassis, or replacing both units of a pair at once — and only if the higher-wattage model appears on the vendor's supported list for that chassis. The PSU bay, connector, and midplane are generation-specific even when the form factor looks identical.

Why mixed-wattage pairs are unsupported

Redundant supplies load-share, and the system's power budget is calculated from what a single supply can deliver if its partner fails. Mix a 750W and an 1100W unit and that calculation breaks: most platforms respond by logging a PSU mismatch event, marking redundancy as lost, or refusing to bring the mismatched unit online at all. Even where the server keeps running, behavior under a real failure becomes unpredictable — exactly the condition redundancy exists to protect against. If you need more headroom, replace both supplies together.

Hot-swapping the failed unit

Redundant PSUs are designed to be replaced with the server running. The procedure is short, but do it in order:

1. Confirm in iDRAC, iLO, or your BMC which slot holds the failed supply, and that the surviving unit shows healthy and carrying the full load.
2. Verify the amber fault LED on the physical unit matches the slot the controller reported. Pulling the healthy supply takes the server down.
3. Unplug the AC cord from the failed unit, release the latch, and slide it out.
4. Insert the replacement until it latches, connect power, and wait for the status LED to go green.
5. Check that the management controller reports redundancy restored before closing the ticket.

When the label is unreadable

Burnt, oily, or faded labels are common on failed supplies. You still have three routes to the part number:

• Read the surviving twin. In a matched redundant pair, the healthy unit carries the same part number.
• Query the management controller. iDRAC, iLO, and most BMCs record the installed PSU model and part number in hardware inventory, often even for a failed unit.
• Look up the system identifier. A Dell service tag, HPE serial number, or Lenovo machine type-model resolves to the original factory configuration, including the shipped PSU part number.

We stock supplies for both current and end-of-life server generations, every unit ships with a 3-year warranty, and in-stock parts ordered before 12 PM EST ship the same day.

Not sure which number on the label is the right one? Send us the part number, the service tag, or just the server model, and our sales team will match the correct replacement power supply and confirm compatibility for free before you order.