ATX 3.0 PSU Spec Loophole Lets Mfrs. Evade Stringent Excursion Tolerance Test


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HDMI 2.1 all over again?

EDIT: The original article from techPowerUp!, an excerpt of which can be read below, contained an error. It stated that the more stressful transient response test measured an ATX 3.0 power supply’s ability to handle a 200% excursion for at least 100 ms (milliseconds). This correct unit of measure was µs (microseconds). This error has been corrected, and the excerpt of the article in this post has been updated to reflect that.

When testing recent high-end GPU launches such as the AMD Radeon RX 6950 XT graphics card, we observed some system reboots that caused due to power-draw spikes (technically known as "excursions"). This is when a graphics card, for a brief moment, draws more power than the connector is capable of supplying, triggering the PSU's electrical protections, and causing a reboot. The new ATX 3.0 specification for the next-generation of desktop PC power supplies enable PSUs with a high tolerance for excursions, and prescribes testing standards to ensure a PSU meets the ATX 3.0 spec. Aris Mpitziopoulos (crmaris) and Jon Gerow (Jonnyguru) discovered wording in the latest Intel ATX 3.0 specification that could make you pay closer attention to reviews of ATX 3.0-spec PSU, when they're out.

In a Hardware Busters article, Mpitziopoulos clears the confusion that the ATX 3.0 power supply specs by Intel and the PCI-Express 5.0 power specification by the PCI-SIG, are mutually-inclusive—they're not. An ATX 3.0 PSU is not required to include a 12+4 pin (or 16-pin) ATX 12VHPWR connector, whether or not their nameplate Wattage is above 450 W, which means it's subjected to passing less stressful transient-response tests, particularly the ability to deal with a 200% excursion for at least 100 µs.

Sources: techPowerUp!, Hardware Busters
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So the PSU-makers can basically slap an atx 3.0 sticker on their old stock of high end units then?
So the PSU-makers can basically slap an atx 3.0 sticker on their old stock of high end units then?

Possibly. ATX 3.0 PSUs without the 12VHPWR connected still have to pass transient response tests, albeit less strenuous ones.

Also, I think that there is a mistake in the techPowerUp article. I think the author said “100 ms” when they meant to say “100 μs.” Take a look at the chart in the full article.

EDIT: The author of the article fixed the error.
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