GPU Power Supply & Cooling Sizer
Calculate the minimum PSU wattage, required PCIe/EPS cables, heat output, and case airflow for multi-GPU AI inference or mining rigs.
Hardware inputs
GPU(s)
Host system
Cooling & case
PSU sizing
Estimated DC load
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Wall draw: —
Recommended PSU
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Recommended 12V rail: —
Heat output
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— watts as heat
Target case airflow
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—
12VHPWR cables
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8-pin PCIe cables
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EPS 12V 8-pin cables
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6-pin PCIe cables
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Verdict
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Frequently asked questions
Why do I need a PSU headroom buffer?
GPUs can spike well above their TDP for milliseconds under load. A 20-30% headroom buffer keeps the PSU in its efficient range, reduces fan noise, and absorbs transient peaks without shutdowns.
How many PCIe power cables do I need?
Each 12VHPWR cable supplies up to 600 W. Each 8-pin PCIe cable supplies up to 150 W (plus the slot's 75 W for older cards). The calculator sums connector counts across selected GPUs.
Does the calculator account for wall draw?
Yes. DC load is what components draw internally. Wall draw is DC load divided by PSU efficiency. We display both so you can size circuits and cooling.
What case airflow do I need for an AI rig?
Rough rule: 2.5 CFM per 100 W of heat output for average cases. Poorly ventilated cases need more; cases with mesh fronts and exhaust fans need less. Hot ambient rooms add a penalty.
Can this size a mining-style open frame?
Yes. Pick the Custom/Other GPU and set the count. Open frames get the 'good' airflow multiplier by default because there is no case restriction.
Figures are typical TDP and connector values for common AI inference and mining GPUs. Actual peak draw varies by workload, overclock, and transient spikes. Size PSU at 80-90% of rated capacity for steady-state loads and leave headroom for spikes.