Updated October 1, 2026 · 6 min read
Sizing a power supply without guesswork
How we estimate peak draw, why headroom matters, and what the 12V-2x6 connector changes.
Start from real component draw
A power supply should be sized from the components that actually draw power: the processor's sustained package power (not just its marketing TDP), the graphics card's rated board power, and a modest allowance for the motherboard, memory, drives and fans.
Avalon's configurator adds these up and shows each contributor and its basis. If any major figure is missing, it says the estimate is unknown rather than assuming.
Why we add headroom
Modern graphics cards produce brief power spikes above their rated draw. Running a power supply near its limit also makes it louder and hotter. We recommend capacity of roughly 30% above estimated peak, rounded up to the next 50 W.
More headroom is not always better — an oversized unit costs more and can be slightly less efficient at idle.
Connectors matter as much as watts
Recent high-end graphics cards use a single 12V-2x6 (formerly 12VHPWR) connector. A power supply with a native cable avoids bulky adapters. If a supply only has 8-pin leads, the card's adapter typically needs three or four of them.
The configurator checks connector availability and warns when an adapter is required.