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PSU Voltage Ripple [Explained]

A PSU voltage ripple is the unwanted fluctuation in the DC voltage output of a power supply unit which means the output has an AC component.

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Voltage ripple is a technical specification that casual users often overlook when they buy a PSU for their system. Yes, it plays a crucial role in your PC’s overall performance. PSU voltage ripple has more significance, especially if you’re an overclocker or an enthusiast.

Key Takeaways

  • Voltage ripple in a PSU is the unwanted fluctuation in the DC voltage output, which means an AC component is present.
  • Lower voltage ripple is crucial for system performance. Otherwise, it can cause system failure and become a hurdle in overclocking. 
  • High-quality power supplies have voltage ripples lower than 20 mV, but below 30 mV are also acceptable for 12V PSU rails.

What Is PSU Voltage Ripple?

A PSU voltage ripple is the unwanted fluctuation in the DC voltage output of a power supply unit. We can also say that the output power has an AC component[1].

However, due to the nature of AC-DC conversion, slight variations in voltage always occur[2]. These fluctuations are measured in millivolts (mV), the difference between the highest and the lowest voltage points in the cycle[3].

PSU Voltage Ripple
SIDE PSU (Image By Tech4Gamers)

Why Does PSU Voltage Ripple Matter?

The voltage ripple might seem like a minor specification, but it drastically impacts your PC performance. Here’s why:

  • Stability: The higher voltage ripple can stress the sensitive components of your PC, such as your CPU and GPU. Premature component failure, crashes, and instability may occur due to voltage ripple.
  • Overclocking: As you know, overclocking involves pushing the component beyond its default factory setting, so it requires a stable and potent PSU. Higher voltage ripple can sabotage overclocking and limit the maximum stable frequencies.

What Is Good Ripple Performance?

According to the ATX specifications[4], the ideal voltage ripple for:

  • 12V rails have a maximum of 120 mV peak-to-peak and for the
  • 3.3V and 5V rails, the ripple is a maximum of 50 mV.

However, this is a rather far-fetched case. In fact, as per our testing, a high-end stable PSU will showcase a maximum ripple of below 20 mV, while a decent (average) PSU can have up to 30 mV of voltage ripple. Take a look at some of our test results:

Helpful Resources By Tech4Gamers:


  1. POWER SUPPLY BASICS – Wavelength Electronics. (n.d.).
  2. Understanding AC/DC Power Supply | Article | MPS. (n.d.).
  3. Lee, Y. S., & Chow, M. H. (2011, January 1). Diode Rectifiers. Elsevier eBooks.
  4. INTEL – ATX Specification (n.d.).

Frequently Asked Questions

What is ripple voltage in a power supply?

The ripple voltage in a PSU is simply a residual periodic variation or fluctuation in the DC voltage.

What is an acceptable ripple for PSU?

Considering the actual scenarios, the ripple lower than 30mV in the PSUs is acceptable. However, ATX specifications have a maximum limit of 120 mV.

How do I reduce my PSU ripple?

You can reduce the voltage ripple in your PSU by stabilizing the AC frequency and load. However, you can’t directly modify the specifications, so buy a good PSU instead.

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