Igor's Lab conducted an in-depth analysis of the power management system of the new NVIDIA GeForce RTX 5090 graphics card, including the way the card draws peak power within the tolerances of the ATX 3.1 specification. This analysis should prove particularly useful for those still on older ATX v2.51 PSUs, and plan to use the included power adapter that converts four 8-pin PCIe power connectors to a 12V2x6. Igor's peak power analysis shows that the RTX 5090 is capable of excursions as high as 627.5 W for 10 ms to 20 ms durations; as high as 738.2 W in 5 ms to 10 ms durations, as high as 823.6 W in the 1 ms to 5 ms category, and as high as 901.1 W in spikes under 1 ms in duration.

An excursion is a brief increase in power draw beyond the continuous power delivery limit of the connector (600 W in case of the RTX 5090's single 12V2x6 input and adapter that converts four 150 W 8-pin PCIe inputs). There is nothing particularly alarming about these numbers, and the excursions part of Igor's analysis fall within the specification of the ATX 3.1 standard, which calls for excursions of up to 200% (1200 W) up to 1 ms. Any PSU meeting the ATX 3.1 specs that even has a continuous power output of less than 1200 W will be capable of handling these spikes. It's only with the much older generations of PSUs, such as ATX v2.51 (mid-2010s) that excursions can trigger OCP. Find other great insights in the Igor's Lab review linked below.