LLM Power Consumption Guide: Watts Per Token on Every GPU

Power consumption determines your electricity bill and thermal requirements. An RTX 5090 generates twice as many tokens as an RTX 4090 but also draws twice the power. This guide measures efficiency in watts per token — the true metric for running LLMs sustainably.

Efficiency Benchmark: Watts Per Token (8B Model Q4)

GPUTokens/secPower DrawWatts/Token
RTX 5090185 tok/s490W2.6 W/tok
RTX 4090122 tok/s370W3.0 W/tok
RTX 407088 tok/s200W2.3 W/tok
RX 9070 XT60 tok/s220W3.7 W/tok
Mac M4 Pro (14-core)62 tok/s28W0.45 W/tok ★

Apple Silicon Efficiency Advantage

The Mac Mini M4 Pro with its 28W total system power draw is the most efficient local LLM machine per token by a massive margin. For 24/7 inference, the electricity savings over 3 years can offset the higher purchase price. Full efficiency analysis is at LLMHardware.io's efficiency benchmarks.

Electricity Cost Calculator

At $0.15/kWh average US electricity cost:

  • RTX 4090 at 8h/day: 370W × 8h × 365 × $0.15 = $162/year
  • Mac M4 Pro at 8h/day: 28W × 8h × 365 × $0.15 = $12/year
  • CPU-only mini PC at 24h/day: 15W × 24 × 365 × $0.15 = $20/year

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