When a second GPU stops paying for itself

Adding a second card doubles hashrate on paper and more than doubles heat and noise in a small room. Traders near Jongno often discover the second card also pushes the monthly kWh into a steeper bracket.

Signals to pause before buying

• The first card’s margin is already under one thousand won per hashing hour after fees
• Nighttime noise already shortens the schedule below six hours
• The apartment bill sits near a bracket boundary in shoulder seasons

What our reviews usually recommend

Keep the stronger card on the clearest algorithm. Park the second for difficulty dips or cold months when heating would run anyway — only if the electrical circuit and landlord rules allow it. Dual mining is a schedule decision as much as a hardware decision.

If you are weighing a purchase, bring both the current profile and the candidate card’s expected wall watts to a Profitability Review. Buying first and modeling later is how thin margins become surprises.