Power supplies we price
Lowest current eBay price, new or used. All PC parts
How it works
We add the graphics card's board power (the manufacturer's spec), the CPU's maximum package power (AMD PPT or Intel PL2, which is higher than the TDP on the box), about 50 W for the motherboard, memory and USB, 10 W per hard drive, 5 W per SSD and 3 W per fan. The recommendation is the next standard size at or above that total plus 35%, which keeps the supply near the efficient middle of its range and covers short power spikes.
Recent high-end NVIDIA and AMD cards draw brief spikes well above their rated power. For cards over 300 W, an ATX 3.0 or 3.1 supply with a native 12V-2x6 cable is the safer choice. Hard drives draw about 25 W each for a few seconds at spin-up, so large NAS builds need extra margin.
Planning the whole machine? The gaming PC builder prices every part.