Best 100x PSUs in Efficiency @ Light & Super-Light Loads – Hardware Busters

Update Date Changes
21 January 2024 Initial article

This article will show you the best 100x PSUs in Efficiency under light and super-light loads. With electricity prices rising, more and more people care about the efficiency of their PC systems, which is defined by the power supply (PSU) they use. Several years ago, most PSUs sold were Bronze-certified in efficiency, meaning that they weren’t so efficient, but this changed once the cost for Gold-certified PSUs dropped notably. Currently, mostly Gold PSUs are preferred, but there are also big markets, e.g., the Brazilian one, where Bronze PSUs are still preferred due to the affordable price tags.

Since most PC systems spend their time idle or under load, I will show you the most efficient PSUs at these load levels in today’s article. The term that strong PSUs are not efficient at light loads doesn’t apply for quite some time now. To put it gently, this is an urban myth since all modern platforms can operate in “burst mode,” which reduces power consumption by allowing the converter to operate for a predetermined time only and not constantly. You can read this article if you have an electronics background and want to learn more about “burst mode” and its side effects on the PSU’s performance, which include high ripple at light loads and increased EMI. This is why some brands send to the certification agencies their products with burst-mode enabled, while for standard production, they shut it off, which is a significant fraud if you ask me since their buyers believe that the PSUs they bought are highly efficient at light loads, while they are not.

Intel is also pushing hard for more efficient PSUs, especially at light loads, through its ATX specifications on power supply design. The fact is that Intel had to push back a little bit on the super-light load requirements, apparently because the PSU manufacturers complained about the strict requirements.

So, while in the ATX v3.1 spec for multi-12V rail PSUs, the following applies:

Low Load Efficiency 10W / 2%
Required 60%
Recommended 70%

The previous ATX v2.53 spec included the following:

Required Date 12W/2% 10W/2%
September 2017 60%
July 2018 60%
July 2020 70%

So normally, all ATX v3.x compliant PSUs should have at least 70% efficiency with a 2% load, but instead, the requirement is at 60%, and 70% is the recommended (meaning non-mandatory) level. So far, most Gold efficiency and above PSUs I evaluated don’t have a problem exceeding 70% with a 2% load (or 10W for PSUs <500W max power and lower).

For the 20-80W average efficiency results, I won’t use Wattage categories, but I will provide the 100 most efficient Power Supplies. To avoid confusion, I will do the same for the 2% load or 10W for PSUs with a capacity lower than 500W.

To look at the overall efficiency and performance, read my Best ATX v3.x PSUs article.

I will put some affiliate links for the products listed in the graphs. You don’t pay more using these affiliate links, but you help us keep this site alive and kicking! We also have a Patreon page, should you want to support us.

Although the PSUs shown in this article won’t be confined to ATX v3.x compliant only, if you have any questions about ATX v3.x PSUs, the following article contains everything you need to know:

Will my ATX v3.0 PSU or my GPU be compatible with 12V-2×6? Do I need a new cable/PSU/GPU? Everything you need to know!


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