A desktop power supply’s model is usually printed on a label attached to its casing, but that label may face a side panel or be hidden inside a prebuilt computer. This guide shows how to find and read it safely, what to do when it is inaccessible, and which specifications matter when planning a replacement.
Start with the computer’s make and model
Before opening the case, look for the desktop’s brand and complete model or product number. Check the front or rear of the tower, a service tag, or the original purchase and service documents. A manufacturer’s support page may list the installed power supply for that exact configuration, sometimes under specifications, parts, or a service manual.
This is a useful first check for branded desktops, especially compact systems with unusual power supplies. However, a product family can be sold with multiple configurations, and a previous owner may have changed the PSU. A general computer model name is not proof of the power supply currently installed. Treat online specifications as a lead, then confirm the physical unit if practical.
You can also check the invoice, build sheet, or parts list if the computer was assembled or upgraded. Search for terms such as “PSU,” “power supply,” and the manufacturer’s name. Keep the exact model number, not only a broad description such as “650-watt gold PSU.”
Find the label on the power supply
The PSU is the metal box where the desktop’s AC power cord connects. In a typical tower it is mounted at the top or bottom of the case. Its specification label is usually on one of the broad sides, although the label may face inward toward the motherboard or be obscured by a case shroud.
If the label is visible through a side window or an open panel, use a flashlight and take a clear photo. Include the entire label so you can capture the model code, electrical output table, and manufacturer details. A photo is easier to read than trying to copy a long string while leaning into the case.
Open the case only for visual inspection
If you need to remove a side panel, follow the computer or case manufacturer’s instructions. Shut the computer down, switch off the PSU if it has a rear switch, unplug the AC cord, and place the tower on a stable surface. Wait briefly, then remove only the panel needed for viewing. Avoid touching circuit boards or internal PSU components. Do not remove the power supply’s own metal cover; hazardous voltage can remain inside even after it is unplugged.
Do not open a case if doing so would put you at risk, damage a sealed or warranty-covered system, or require moving components you are not comfortable handling. A service technician can identify the unit for you. Never use a screwdriver, paper clip, or other object to probe the PSU or its connectors while it is powered.
If the label faces the opposite side
Some cases hide the label behind the cable-management panel. On others, the label faces the case floor or motherboard tray. Try these options in order:
- Use a flashlight or phone camera through existing openings; avoid inserting objects into the case.
- Check whether the case has a separate cable-side panel that can be removed according to its manual.
- Look for a readable model marking on the visible PSU edge or rear, while recognizing that the rear may show only a brand or series.
- Consult the computer’s service documentation or ask a repair shop to inspect it.
Removing the PSU to expose its label is usually unnecessary for identification. If it is required, treat that as a component-removal job: photograph the cable connections first and use the computer maker’s or PSU maker’s instructions. Do not pull on wires or disconnect modular cables without understanding where each belongs.
Read the model number and label details
The model number is the most useful identifier. It may be labeled “Model,” “Model No.,” “P/N,” or “Part Number,” and is often a mixture of letters, numbers, and hyphens. Record the manufacturer and full code exactly, including suffixes. Similar product names can cover units with different revisions, connectors, or wattages.
The label may also show a series name, serial number, rated output, and a table of voltage rails. These details can help distinguish variants, but do not substitute a serial number for a model number. If the code is faint, search the manufacturer’s support site or documentation using both the model code and series name. Compare the result’s label layout, rated output, and connector information with the unit in your computer; search results can mix revisions or regional variants.
| Label item | What it tells you | How to use it |
|---|---|---|
| Model or part number | The specific PSU variant | Search manufacturer documentation and replacement listings |
| Rated wattage | The unit’s stated total output capacity | Compare with system requirements and upgrade plans |
| +12 V output | Capacity available on a major output rail | Check the manufacturer’s specifications for demanding components |
| Efficiency certification | A rating related to efficiency under defined conditions | Do not treat it as a measure of fit, quality, or compatibility |
| Serial or revision code | A traceability or hardware revision identifier | Provide it to manufacturer support when resolving a variant question |
A printed wattage alone does not establish that a replacement is appropriate. Power supplies differ in physical dimensions, mounting, connector layout, cable type, and output capability. Verify the exact unit’s specifications rather than assuming that products with the same wattage are interchangeable.
When software or the operating system cannot help
Windows, macOS, and common hardware-monitoring utilities generally do not report a standard desktop PSU’s model. The supply ordinarily provides power, not a digital inventory record of its brand and product code. Motherboard tools may show voltage readings, but those readings do not identify the PSU and should not be used to infer its exact model.
There are exceptions: some newer digital power supplies connect to monitoring software over an internal USB link or a vendor-specific controller. If the system already has such software installed, it may display a product name. Treat that as a clue, then confirm with the label or documentation if the exact revision matters. Do not install unknown software or connect cables just to identify a PSU.
If the label cannot be seen and the computer is a prebuilt system, use the full system model and service tag on the manufacturer’s parts lookup. For a custom PC, check the original build notes, receipts, or old photographs. If none are available, a technician can inspect it. The visible shape of the case or a rough wattage estimate cannot reliably establish the model.
Verify fit before buying a replacement
Once you have the model, identify the reason for replacement and the components the PSU must support. Then check the computer or motherboard manufacturer’s guidance and the PSU maker’s product documentation. Confirm the following:
- Form factor and dimensions: ATX is common in towers, but compact computers may use SFX, TFX, proprietary sizes, or an external power adapter. Check clearance, mounting points, and case depth.
- Motherboard and CPU power: Confirm the required main motherboard connector and CPU power connectors. A connector that appears similar may not have the same pinout or intended use.
- Graphics card power: Check the exact card’s required connectors and the PSU manufacturer’s guidance. Some cards use newer high-power connectors; use only the cables and adapters approved for the specific equipment.
- Capacity: Compare the PSU’s rated output and manufacturer recommendations with the full system configuration, including a planned graphics card or processor upgrade. Leave appropriate headroom, but do not select by wattage alone.
- Cable arrangement: A modular PSU can make cable routing easier, but modular cables are not universally interchangeable. Even cables from the same brand can differ between product families. Use only cables listed as compatible with that exact PSU model.
- Efficiency and protections: Review the manufacturer’s specifications for efficiency ratings and built-in protections. These features can inform a choice, but they do not override size, connector, or capacity requirements.
A PSU that physically fits may still be electrically incompatible. This matters particularly in OEM desktops, where motherboard power connectors or case dimensions can differ from common retail standards. If documentation does not clearly confirm compatibility, contact the computer or PSU manufacturer with both model numbers before purchasing.
Troubleshoot a missing, damaged, or confusing label
A missing label does not mean the PSU is safe to open. Do not peel back covers, scrape the casing, or remove the PSU’s electrical enclosure to look for a hidden identification plate. If the outside label is torn or unreadable, use receipts, build records, manufacturer support, or a qualified repair service.
If the label lists several model-like codes, record all of them and note which field each appears beside. The part number is often the best key for a product search; the serial number usually identifies an individual unit. A revision code can matter when a manufacturer has changed cables or specifications without changing the retail series name.
If you find multiple PSU models listed for the same prebuilt computer, verify the exact configuration by service tag or serial number through the manufacturer’s parts lookup. If that still leaves uncertainty, a physical inspection is the most reliable route. Do not order based only on a forum post about a similar-looking computer.
If the computer is shutting down, restarting, or failing to start, identifying the PSU can help you find its documentation, but it does not prove the PSU caused the fault. Those symptoms can have other causes. Avoid repeatedly cycling a system that smells burnt, makes unusual electrical noises, or shows visible damage. Shut it down, unplug it, and arrange a qualified inspection. Never open or electrically test the PSU unless you are trained and equipped to do so.
Keep the information for future upgrades
Save a photo of the label and write down the manufacturer, exact model or part number, rated wattage, and approximate purchase date if known. Keep the PSU manual and cable compatibility notes with the computer’s build records. For a prebuilt machine, also record the full system model and service tag in your own equipment inventory.
Before a future upgrade, check the new component’s official requirements against the PSU model documentation and the computer case’s physical limits. Recheck connector and cable compatibility whenever replacing the supply, even if the old and new units share a brand or wattage. This small record makes troubleshooting and workstation planning more reliable.