Wall meters beat TDP stickers

Thermal design power is a cooling hint, not a wall promise. Undervolt curves, riser inefficiency, and PSU load curves all sit between the GPU die and your meter.

A fifteen-minute habit

Plug the mining PC into a simple energy meter. Idle for five minutes, then load your usual miner for ten. Note average watts. That number belongs in every profitability sheet.

Dual-card surprises

Two “120 W” cards rarely draw 240 W at the wall once the board, NVMe, and fans join. We routinely see 15–25% overhead. Ignoring it turns a thin margin into a quiet loss.

When verification helps

If your pool hashrate looks healthy but the bill stings, book hashrate & power verification. We reconcile dashboard figures with the meter so the next estimate starts honest.