Apple iMac Power Supply Unit (PSU) Replacement

Is your iMac completely dead, not turning on, or shutting down randomly? It could be a faulty power supply unit (PSU). The PSU is responsible for delivering power to all the internal components — and when it fails, your iMac won’t start at all.

Common symptoms of PSU failure include no power response when pressing the power button, a sudden shutdown during use, clicking or ticking noises, or visible signs of electrical damage. These issues can be caused by age, electrical surge, overheating, or internal short circuits.

At Safemode, we provide professional PSU replacement for all iMac models — including 21.5″, 24″, and 27″ versions. We use high-quality parts and follow proper safety procedures to bring your iMac back to life.

Pricing Breakdown

Typical Apple iMac power supply unit (PSU) replacement starts from $380 to $450+, depending on your iMac model, the power rating of the PSU, and the availability of replacement parts.

Here’s how the pricing usually breaks down:

• $380–$450 → For most 21.5″ and 27″ iMac models, especially Intel-based systems with standard PSUs (typically 185W–300W units). These are common and relatively straightforward to replace once the screen is removed.

• $550–$650+ → For high-end iMac models, such as the iMac Pro or Retina 5K models with higher-wattage PSUs. These units often require:

  • Higher-capacity power supplies (e.g. 360W–500W)

  • More complex internal layouts

  • Specialised or less commonly stocked replacement parts

What affects the cost:

• iMac size and model year
• PSU wattage (higher wattage = higher cost)
• Labour required to remove and reseal the display
• Availability of genuine or compatible PSU units

➡ If your iMac isn’t powering on, frequently shuts down, or shows signs of unstable performance, a failing PSU could be the cause.
➡ At Safemode, we test the power output, replace faulty power supplies, and fully check all system components before final assembly.

Our Process

• Initial Power Check – We test your iMac for signs of power, including fan movement, LED indicators, and voltage levels. We also test your power cable and external power connection.
• Disassembly – We carefully remove the iMac screen using specialised tools to access the internal components. The PSU is usually located behind or beside the logic board and may require removing other parts for access.
• PSU Replacement – We install a high-quality replacement power supply unit matched to your iMac’s model, year, and power requirements.
• Reassembly & Cable Check – After replacing the PSU, we reassemble the iMac and double-check all internal connections, including to the logic board and display.
• Final Testing – We confirm stable power delivery, check for system boot, and monitor the iMac under load to ensure the new PSU is working properly.

The Technical Stuff

iMac PSU designs vary across generations and sizes:

• 21.5″ & 27″ Intel iMacs – Use internal AC-DC power supply modules ranging from 185W to 310W.
• Retina 5K iMacs – Require higher wattage PSUs with specific connectors for the display and logic board.
• M1/M3 iMacs (24″) – Use external power adapters with magnetic connectors (includes Ethernet in some models); internal PSU replacement not required.
• Voltage testing – We use multimeters to check output rails (e.g. 12V, 3.3V, 5V) before and after installation.
• Surge damage – Failed PSUs can sometimes damage logic boards; we always inspect for further issues during diagnosis.

We install only compatible PSUs and test thoroughly to ensure long-term reliability.

Our Difference

iMac PSU replacement isn’t as simple as plugging in a new power brick. These systems are sealed, and opening them without damaging the display requires care and experience. At Safemode, we’ve replaced power supplies in thousands of iMacs — and we do it cleanly, safely, and correctly.

We also test beyond just powering on — making sure your iMac runs stably under real-world conditions.

At Safemode, we don’t just bring your iMac back to life — we make sure it stays that way.