About PowerMyPC

PowerMyPC is a free, fast power supply calculator built for PC builders and upgraders. We don't use display ads or pop-ups, and we don't ask you to sign up. We keep the lights on with affiliate links (see disclosure), and those links never change our numbers.

Methodology

• CPU: We use each processor's sustained power limit (AMD PPT, Intel PL2/Maximum Turbo Power). For X3D chips, which rarely reach their limit, we use measured all-core power. Gaming draw uses typical measured values. Overclocking adds 20%.
• GPU: We use the reference total board power. Factory-overclocked partner cards can draw 5 to 15% more, and the overclock toggle adds 10%.
• Spikes: Millisecond-scale excursions are estimated per generation: about 1.8× for RTX 30, about 1.6× for RX 6000, and about 1.4 to 1.5× for RTX 40, RTX 50, RX 7000, RX 9000 and Arc. ATX 3.x units are assumed to tolerate excursions of about 1.5× their rating. Older units are assumed to tolerate about 1.1×.
• Everything else: Motherboard 50 W, 5 W per memory stick, 7 W per NVMe SSD, 4 W per SATA SSD, 8 W per hard drive (plus spin-up), 3 W per fan, 3 to 25 W for cooling pumps, 0 to 20 W for RGB and 5 to 25 W for USB.
• Sizing: Recommended = sustained load at or below 80% of rating and spikes within ATX 3.x tolerance, rounded up to a common size. Minimum allows up to 90% sustained load.
• Running cost: Gaming wall power assumes about 90% PSU efficiency, plus up to 4 hours a day of light desktop use.

These are careful estimates, not lab measurements. When in doubt, follow your graphics card maker's guidance and choose the larger size. Spot an error or a missing part? Email hello@powermypc.com. We update the database regularly.