Chain X Only Fix — Antminer Missing Hashboard Troubleshooting Guide

What This Error Means

The “Chain X Only” error — also displayed as missing hashboard, “Chain 0 only,” “Chain 1 only,” or seeing only 1 or 2 out of 3 hashboards detected — means your Antminer control board is failing to communicate with one or more hashboards. Instead of detecting all three hash chains during initialization, the miner only registers a partial set. This is one of the most common Antminer errors and affects virtually every model from the S9 through the S21 series.

When your miner dashboard shows fewer chains than expected, the missing hashboard is either physically disconnected, electronically damaged, or failing to pass the initialization handshake with the control board. Your miner will continue to operate on the remaining chains, but at reduced hashrate — losing roughly 33% of capacity per missing board.

Common Causes

• Loose or damaged ribbon cable — The flat data cable connecting the hashboard to the control board has worked loose due to vibration, or the connector pins are bent or corroded. This is the most common cause and the easiest to fix.
• Hashboard connector corrosion — Humidity or condensation has caused oxidation on the connector pins between the hashboard and control board, creating an intermittent or broken connection.
• Failed hashboard — One or more ASIC chips on the hashboard have died, preventing the board from completing its initialization sequence. The control board sees the board as non-responsive.
• Control board fault — The control board itself has a damaged hash chain port. One of the three data interfaces on the control board has failed, making it unable to communicate with the hashboard plugged into that port.
• Power delivery issue — The hashboard is not receiving adequate voltage from the PSU. A damaged power connector, broken trace on the hashboard power input, or failing PSU rail can prevent the board from powering up.
• Firmware or configuration corruption — A corrupted firmware flash or incorrect configuration file can cause the miner to fail to initialize one or more chains during boot.

Step-by-Step Fix

Safety first: Always power off the miner completely and disconnect it from the power supply before opening the case or touching any internal components. ASIC miners operate at high voltages that can cause serious injury.

Step 1: Identify the Missing Chain

Log into your miner web interface (typically at the miner IP address in your browser). Navigate to the Miner Status or Dashboard page. Note which chain number is missing. On most Antminers, chains are numbered 0, 1, and 2 (or 6, 7, 8 on some S19 variants). Document the exact error message and which chains are reporting.

Step 2: Power Cycle the Miner

Before opening anything, perform a full power cycle. Shut down the miner through the web interface, wait 30 seconds, unplug the power cables, wait another 60 seconds, then reconnect and power on. Approximately 15-20% of chain detection failures are transient and resolve with a clean reboot.

Step 3: Reseat the Ribbon Cables

Power off and unplug the miner. Open the case and locate the flat ribbon cables connecting each hashboard to the control board. Carefully disconnect each ribbon cable, inspect the connector for bent pins or debris, and firmly reseat it. Make sure the locking tab (if present) clicks into place. This single step resolves the majority of Chain X Only errors.

Step 4: Swap Ribbon Cables Between Chains

If reseating does not resolve the issue, swap the ribbon cable from the working chain with the cable from the non-working chain. If the problem follows the cable, you have a bad ribbon cable — replace it. If the problem stays on the same port, the issue is either the hashboard or the control board port.

Step 5: Test the Hashboard on a Different Port

Move the suspect hashboard data cable to a different control board port (the port that was previously working with a different chain). If the hashboard now works on the new port, the original control board port is damaged. If the hashboard still fails on the new port, the hashboard itself is the problem.

Step 6: Inspect Power Connections

Check the power cable connections to the suspect hashboard. Each hashboard receives power directly from the PSU through heavy-gauge cables. Ensure these are fully seated and that the connectors show no signs of melting, discoloration, or damage. A multimeter reading at the hashboard power input should show the expected voltage (varies by model — typically 12-14V for older models, higher for newer ones).

Step 7: Flash Fresh Firmware

If the physical connections all check out, download the latest official firmware for your specific model from Bitmain and perform a clean flash via the web interface (System > Upgrade). Alternatively, use an SD card flash for a complete firmware reinstall. This eliminates any software-level chain detection issues.

Advanced Diagnosis

For technically inclined miners comfortable with SSH access and command-line diagnostics:

Check kernel logs for chain initialization:

ssh root@[miner-ip]
cat /var/log/messages | grep -i "chain"
dmesg | grep -i "hash"

Look for initialization timeout messages, voltage regulation errors, or chip enumeration failures. The kernel log will typically show exactly where the chain initialization sequence fails — whether at the voltage regulator stage, the chip detection stage, or the communication handshake stage.

Test individual chip responses (S9 and similar):

cat /var/log/messages | grep "chip"
# Look for lines showing chip count per chain
# A healthy S9 shows ~63 chips per chain

If the log shows the chain starting initialization but failing partway through chip enumeration, you likely have a dead chip that is breaking the daisy-chain communication. This requires board-level repair — specifically identifying and replacing the failed ASIC chip.

Voltage domain testing: On models with multiple voltage domains per hashboard (S17+, S19 series), a single failed voltage domain can take down an entire chain. Check the kernel log for voltage domain-specific errors, which will point to the specific section of the hashboard that has failed.

When to Get Professional Help

You should seek professional ASIC repair if:

• The hashboard fails on multiple control board ports, confirming a board-level fault
• Kernel logs show chip enumeration failures — this means dead ASIC chips that require micro-soldering to replace
• You see burn marks, discoloration, or physical damage on the hashboard
• The control board has a damaged port — control board repair requires specialized equipment
• The problem persists after cable replacement, port swapping, and firmware reflash

D-Central Technologies has repaired over 2,500 ASIC miners with a 95%+ success rate. Our technicians perform chip-level diagnostics and board-level micro-soldering on every Antminer model from the S9 through the S21 XP. Submit a repair request here

Affected Models

This error affects virtually all Antminer models with multiple hashboards, including: S9, S9i, S9j, S15, T15, S17, S17+, S17 Pro, S17e, T17, T17+, S19, S19 Pro, S19j Pro, S19 XP, S19k Pro, S21, S21 XP, T19, T21, L3+, L7, D7, and their variants. The diagnostic process is similar across all models, though the specific chain numbering and connector types vary.

Related Error Codes

• ASIC Chip Error / Dead ASIC — Individual chip failures that can cause chain detection issues
• Low Hashrate / Hashrate Drop — A chain that partially initializes may report low hashrate instead of missing
• EEPROM Error — Corrupted EEPROM data can prevent hashboard detection
• Voltage Error / Voltage Too Low — Power delivery failures that prevent chain initialization
• Whatsminer Hashboard Error — The equivalent error on Whatsminer hardware

Frequently Asked Questions