Our reference database covers fourteen legacy models that South Korean operators still run in meaningful quantities. Below is a summary of the eight most common units we assess, with stock specifications and our general tuning viability rating.

ModelStock Hash RateStock PowerEfficiencyTuning Viability
Antminer S9 (14 TH/s)14.0 TH/s1,372 W98 J/THHigh — stable at 11–12 TH/s, ~950W
Antminer S9i (14 TH/s)14.0 TH/s1,320 W94 J/THHigh — improved PSU efficiency over S9
Antminer S9j (14.5 TH/s)14.5 TH/s1,350 W93 J/THHigh — similar tuning profile to S9i
Whatsminer M20S (68 TH/s)68.0 TH/s3,360 W49 J/THModerate — 58–62 TH/s at ~2,800W achievable
Whatsminer M21S (52 TH/s)52.0 TH/s3,520 W68 J/THModerate — efficiency gains limited by PSU
AvalonMiner 1066 (50 TH/s)50.0 TH/s3,250 W65 J/THModerate — firmware tuning more effective than voltage
AvalonMiner 1047 (37 TH/s)37.0 TH/s2,200 W59 J/THHigh for its class — often overlooked
Antminer T9+ (10.5 TH/s)10.5 TH/s1,433 W136 J/THLow — viable only with very cheap electricity

How to Read Viability Ratings

High means we regularly achieve 15–25% power reduction with less than 8% hash-rate loss, and the tuned profile remains stable through summer ambient temperatures above 35°C.

Moderate means meaningful gains are possible but model-specific — some units respond well to firmware adjustments while others need hardware modifications (fan upgrades, thermal paste replacement) before tuning delivers results.

Low means the machine can be tuned, but break-even economics depend heavily on electricity rates below ₩80/kWh. We still assess these units when clients need documentation for decommissioning decisions.

Models Not Listed

We also maintain reference data for Antminer S17 (53 TH/s), Whatsminer M30S (86 TH/s), Innosilicon T2T-37T, and several other units above the 0.05 TH/s threshold. If your model is not listed, mention it in your inquiry — we will confirm whether it is in our database or requires a new-model research fee.

Quarterly Updates

Specifications and viability ratings are revised each quarter based on network difficulty changes and firmware releases. Last updated: August 2026.

Ask About a Specific Model