ATX 3.0 PSU Specification Loophole Lets Manufacturers Evade Stringent Excursion Tolerance Testing by Simply Excluding the 12+4 pin Connector

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 ms.