How to Quiet Your Antminer S21 at Home: The Complete Guide

If you've ever turned on an Antminer S21 indoors, you already know the problem. At 75–80 dB, it sounds like a vacuum cleaner that never turns off. That's fine in a data center, but if you're mining at home — in your garage, basement, or spare room — that noise level makes it nearly impossible to live with.

The good news? With the right shroud kit, an inline duct fan, and about 30 minutes of setup time, you can get your S21 down to under 50 dB — quieter than a normal conversation. This guide walks you through exactly how to do it, step by step.

Why Is the Antminer S21 So Loud?

The Antminer S21 (200 TH/s) pulls around 3,500W and generates roughly 12,000 BTU/h of heat — equivalent to a medium-sized space heater. To keep the chips from overheating, Bitmain packs it with four high-speed fans that move massive amounts of air. Those fans are designed for industrial mining farms where noise doesn't matter, not for the room next to your bedroom.

Here's how the S21 family compares on noise:

Model Hashrate Power Noise Level Fan Config
Antminer S21 200 TH/s 3,500W ~75 dB 4x 120mm fans
Antminer S21 Pro 234 TH/s 3,510W ~76 dB Different fan layout
Antminer S21 XP 270 TH/s 3,645W ~76 dB Different fan layout
Antminer S21 XP Hyd 473 TH/s 5,676W ~50 dB Liquid-cooled

To put 75 dB in perspective: a normal conversation is about 60 dB, and a vacuum cleaner is around 70–80 dB. The decibel scale is logarithmic, so 75 dB is roughly 5–6 times louder than 50 dB in terms of perceived sound. That's the difference between "I can hear it from upstairs" and "I forget it's running."

The 3 Methods to Quiet Your S21 (Ranked by Effectiveness)

There are three main approaches, and they work best when combined:

Method 1: Shroud Kit + Inline Duct Fan (Best Overall)

This is the gold standard for home miners and the approach we recommend. A shroud is a 3D-printed enclosure that attaches to the intake and exhaust sides of your miner, funneling all airflow into a standard 8" or 10" round duct. You then connect flexible ducting to an inline duct fan (like the AC Infinity Cloudline series), which pulls air through the miner at a controlled, quieter speed.

Why it works: The stock fans on the S21 are the main noise source. By attaching shrouds and using an inline fan to assist airflow, the miner's stock fans don't need to spin as hard, reducing noise dramatically. Combined with ducting the hot exhaust air outside (or into another room you want to heat), you can bring effective noise levels down to 40–50 dB.

What you need:

  • A shroud kit — matched to your exact miner model. This is critical because the S21 (standard) uses dual 120mm fans, while the S21 Pro, S21 XP, and S21+ have a different fan layout. Using the wrong shroud won't seal properly and you'll lose efficiency.
  • An 8" inline duct fan — we recommend the AC Infinity Cloudline S8 Pro (807 CFM, 39 dBA). It's powerful enough to cool an S21 and whisper-quiet at full speed.
  • 8" flexible aluminum ducting — to route the hot air wherever you want it (outside, into another room, or through a wall).
  • 8" hose clamps — to secure the ducting to the shroud and fan.

Our shroud kits for S21 miners:

Method 2: Fan Spoofers + Aftermarket Fans

This approach replaces the stock fans entirely. A fan spoofer tricks the miner's controller into thinking the stock fans are still running, so it doesn't throw error codes. You then replace the stock fans with quieter aftermarket options (like Noctua industrial fans) or use them with an inline fan setup.

Fan spoofers typically reduce noise by 10–20 dB when paired with quieter fans. The trade-off is that aftermarket fans usually move less air than the stock fans, so you may need to undervolt or accept slightly higher operating temperatures.

Shop our ASIC Miner Fan Spoofers →

For a more advanced option, our Njord Board provides automated fan speed control based on temperature — it dynamically adjusts fan speed so you get the quietest operation possible without overheating.

Method 3: Location + Insulation (The Free Option)

If you're not ready to invest in hardware, you can reduce perceived noise simply by putting the miner in the right spot:

  • Garage or basement — concrete walls and distance from living spaces absorb and block sound naturally.
  • Dedicated closet or utility room — with proper ventilation, even a closet can work if you duct the exhaust out.
  • Distance — every doubling of distance from the source reduces noise by about 6 dB. Moving your miner from 1 meter away to 4 meters away cuts perceived loudness roughly in half.

This method alone won't get you to "quiet," but it stacks well with Method 1 for the best results.

Step-by-Step: Installing a Shroud Kit on Your Antminer S21

Here's how to set up a complete noise reduction system. Total time: about 30 minutes.

Step 1: Choose the right shroud kit. Make sure you match the kit to your exact model. The standard S21 uses our S21/S19 Wall-Mount Kit. The S21 Pro, XP, and S21+ use our S21 Pro/XP Kit. These are NOT interchangeable.

Step 2: Power off your miner and disconnect it from the wall. Let it cool for a few minutes.

Step 3: Remove the stock fan grilles on the intake and exhaust sides using the included M4 screws (our kits come with replacement screws).

Step 4: Attach the intake shroud to the intake side. Our shrouds have a screwless PSU slip-on design that captures the PSU outlet with a gasket seal — no air leaks around the power supply.

Step 5: Attach the exhaust shroud to the exhaust side. Secure the 8" duct clamp (included) to the exhaust outlet.

Step 6: Connect your ducting. Run 8" flexible aluminum duct from the exhaust shroud to your inline fan (AC Infinity Cloudline S8 or similar). Then run more ducting from the fan to your exhaust point — a window, dryer vent, or through-wall vent.

Step 7: Connect the intake. Run ducting from the intake shroud to your fresh air source (a vent, window, or just leave it open if the room has good airflow).

Step 8: Power on and test. Start your miner, set your inline fan to medium-high, and check temperatures in your miner's dashboard. Chip temps should stay under 85°C. Adjust fan speed as needed.

Bonus: Use Your S21 as a Home Heater

Here's something most miners don't think about: your S21 produces roughly 12,000 BTU/h of heat. That's the equivalent of a medium-sized space heater — except this one earns you Bitcoin while it heats your home.

If you're in a cold climate (hello, fellow Canadians 🇨🇦), you can duct the hot exhaust air from your miner directly into your living space during winter. This effectively turns your electricity cost into both mining revenue AND heating, dramatically improving your overall economics.

With a proper shroud and ducting setup, you route the hot air exactly where you want it — into the basement, up through floor vents, or into an adjacent room. In summer, duct it outside. This dual-purpose setup is increasingly popular among home miners in Canada and northern climates.

Companies like Canaan even launched dedicated Bitcoin mining home heaters at CES 2025, validating this trend at the industry level.

Recommended Setup: Our Top Pick for S21 Home Mining

Here's the exact setup we recommend for most home miners running an Antminer S21:

Component Our Recommendation Approx. Cost
Shroud Kit Nakamoto Mining Wall-Mount Silencer Kit $110 CAD
Inline Fan AC Infinity Cloudline S8 Pro (807 CFM, 39 dBA) ~$130 CAD
Ducting 8" flexible aluminum duct (10–25 ft) ~$25–50 CAD
Intake Filter (optional) Nakamoto Mining Air Intake Filter Shroud $29 CAD

Total cost: approximately $275–320 CAD — a one-time investment that makes your S21 livable at home and protects your hardware from dust.

Frequently Asked Questions

Will a shroud void my Bitmain warranty?

No. A shroud attaches externally to the fan grille mounting points and doesn't modify any internal components. You're simply redirecting airflow into a duct — the miner itself is untouched.

Can I use a 10" duct instead of 8"?

Yes. A 10" duct moves more air at lower pressure, which can mean even quieter operation. Our 10" Overclock Kit is designed for miners who want maximum airflow for overclocking or who need to run very long duct runs.

Do I need a shroud on both the intake AND exhaust side?

For best results, yes. An exhaust-only setup helps with noise, but you'll still hear the intake fans pulling air from the open side. A full intake + exhaust setup gives you sealed, ducted airflow on both ends for maximum noise reduction.

What if I have an S21 Pro, S21 XP, or S21+?

These models have a different fan layout than the standard S21. You need our S21 Pro/XP/S21+ Shroud Kit — the standard S21 shrouds will NOT fit.

How much noise reduction can I actually expect?

With a proper shroud + inline fan setup, most home miners report effective noise levels of 40–50 dB at 1 meter — down from the stock 75–80 dB. That's roughly the volume of a quiet refrigerator. Results vary based on duct length, fan speed, and room acoustics.

Can I 3D print the shroud myself?

If you have a 3D printer and the right material (PETG recommended for heat resistance), you absolutely can. We're working on offering our STL files for purchase — stay tuned. In the meantime, our pre-printed kits save you 8+ hours of print time and come with all hardware included.

Shop Antminer Noise Reduction Products

Everything you need to make your Antminer quiet enough for home use:

Nakamoto Mining LTD is a Canadian company specializing in 3D-printed ASIC miner accessories. All our shrouds are printed in durable, heat-resistant PETG and ship from Canada with ~3 business day processing. Questions? Contact us.

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