Miner Health Check — Is Your ASIC Performing at 100%?
How to check if your ASIC miner is performing at full capacity using the Diff column. Performance formula, real examples, and troubleshooting.
How do you know if your ASIC miner is actually performing at 100%? The SoloFury dashboard gives you all the data you need. This guide teaches you how to read the Diff column, calculate expected performance, and spot problems before they cost you money.
1. Understanding Dashboard Columns
When you enter your wallet address on the SoloFury dashboard, you see a worker table with these columns:
| Column | What It Means | What to Look For |
|---|---|---|
| Worker | Your miner’s name (e.g., Miner-B) | All your miners should be listed |
| Hashrate | Current mining speed (TH/s, PH/s) | Should match miner specs ±10% |
| Best Diff | Highest difficulty share found (this session) | Higher = closer to finding a block |
| Last Share | Time since last accepted share | Should be seconds, not minutes |
| Shares | Total shares submitted (cumulative work) | Should always increase |
| Diff | Current difficulty assigned to this worker | Key performance indicator |
| Status | Online / Warning / Offline | Should be green “Online” |
2. What is “Diff” and Why It Matters
The Diff (difficulty) column shows the current share difficulty assigned to your worker by the pool’s VarDiff (Variable Difficulty) algorithm.
Here’s the key insight: the Diff value is directly proportional to your miner’s actual hashrate. A miner performing at full speed will have a higher Diff than a miner that’s underperforming.
3. How VarDiff Works
VarDiff automatically adjusts the difficulty for each worker to keep share submissions at a steady rate. Here’s how:
- When a miner first connects, it starts at
startdiff(SoloFury default: 100,000) - If the miner submits shares too frequently, VarDiff increases the difficulty
- If the miner submits shares too slowly, VarDiff decreases the difficulty
- The target is approximately 1 share every 10 seconds (SoloFury’s update interval)
For a powerful ASIC miner like an Antminer S21+ at 235 TH/s, VarDiff will quickly ramp up the difficulty from 100,000 to 300,000+ because the miner produces hashes so fast that low-difficulty shares would flood the pool.
Difficulty timeline for a new S21+ connection:
| Time | Diff | What’s Happening |
|---|---|---|
| 0 min | 100,000 | Miner just connected, starts at startdiff |
| 2 min | 150,000 | VarDiff sees shares coming too fast, increases diff |
| 5 min | 220,000 | Still ramping up |
| 10 min | 300,000+ | Stabilized — shares arriving at the target rate |
4. The Performance Formula
You can calculate the expected steady-state difficulty for any miner using this formula:
Expected Diff = Hashrate (H/s) × Update Interval (seconds)
SoloFury’s update interval is 10 seconds. So:
| Miner | Hashrate | Hashrate in H/s | Expected Diff |
|---|---|---|---|
| Antminer S21+ | 235 TH/s | 235,000,000,000,000 | ~2,350,000,000,000 |
| Antminer S19k Pro | 120 TH/s | 120,000,000,000,000 | ~1,200,000,000,000 |
| Bitaxe Gamma | 1.2 TH/s | 1,200,000,000,000 | ~12,000,000,000 |
5. Real-World Examples
Here is an example of 4 identical Antminer S21+ units mining BCH on SoloFury, taken from a real fleet:
Example 1 — all miners performing well:
| Worker | Hashrate | Best Diff | Current Diff | Status |
|---|---|---|---|---|
| Miner-A | 295 TH/s | 7.593 G | 343,687 | Online |
| Miner-B | 295 TH/s | 31.108 G | 338,815 | Online |
| Miner-C | 279 TH/s | 6.582 G | 301,953 | Online |
| Miner-D | 269 TH/s | 7.031 G | 287,598 | Online |
Analysis:
- All four miners stabilized between 287K and 343K Diff — a ~17% spread, which is normal for ASICs of the same model
- Best Diff for Miner-B (31.108 G) is much higher than the others — this is lottery noise, not a sign of better performance. Best Diff is cumulative and depends on luck
- Hashrate variance (~10%) is also normal day-to-day; what matters is the trend over hours, not individual minutes
6. Comparing Multiple Miners
When you run multiple identical ASICs, comparing them side-by-side is the single most reliable diagnostic technique. Differences between identical hardware almost always indicate a problem.
Example 2 — one miner underperforming:
| Worker | Hashrate | Best Diff | Current Diff | Status |
|---|---|---|---|---|
| Miner-A | 295 TH/s | 7.593 G | 343,687 | Online |
| Miner-B | 295 TH/s | 31.108 G | 338,815 | Online |
| Miner-C | 279 TH/s | 6.582 G | 301,953 | Online |
| Miner-D | 180 TH/s | 1.205 G | 115,000 | Online |
Miner-D is reporting a similar status (Online) but its Diff is nearly 3x lower than the others. Combined with a Hashrate that’s ~40% below spec, this is a clear hardware issue — likely a failed or underperforming hashboard, dirty heatsink, or thermal throttling.
7. Warning Signs — When Something is Wrong
Watch for these red flags on the dashboard:
- Diff dropping below 50% of similar miners’ Diff — likely failed hashboard or thermal throttle
- Hashrate fluctuating wildly (±30% within minutes) — power supply issue or unstable network
- Last Share growing past 60 seconds — miner is stalling or disconnected
- Status flipping Online → Warning → Online — intermittent connection or pool config error
- Best Diff stuck at startdiff (100K) for hours — miner is connecting but not actually hashing (firmware bug)
- Acceptance rate below 99% — could be high latency (wrong region), bad firmware, or hardware errors
8. What To Do When Performance is Low
When you spot an underperforming miner, work through this checklist in order:
- Compare temperatures. Open the miner’s web UI and check chip temperatures. Anything above 85°C on stock firmware = throttling. Clean fans and check ambient air temperature.
- Check power. Verify PSU output voltage and that no breaker has tripped. A failing PSU shows up first as periodic hashrate dips.
- Restart the miner. Sometimes the simplest fix. Reboot from web UI; if no improvement after 10 minutes, power-cycle.
- Test individual hashboards. Most ASIC web UIs show per-board hashrate. A failed board reduces total by ~33% (S21+ has 3 boards).
- Update firmware. BraiinsOS or LuxOS often outperform stock; if you’re on stock, consider switching for diagnostics.
- Check stratum region. A miner in Europe pointed at the US server has high latency stale shares — the Diff numbers will be deceptively low. Switch to
eu-{coin}.solofury.com. - Replace the unit. If individual board tests fail and you’ve ruled out power/thermals, a hashboard or control board may be defective. RMA if under warranty.
Next Steps
- Check your fleet on the SoloFury dashboard right now and compare Diff values across identical miners
- Read the Antminer S21+ Setup Guide if you suspect a config issue
- Use the Coin Switcher to verify you’re mining the most rewarding coin for your hashrate
5. Real-World Examples
Here is an example of 4 identical Antminer S21+ units mining BCH on SoloFury, taken from a real fleet:
Example 1 — all miners performing well:
| Worker | Hashrate | Best Diff | Current Diff | Status |
|---|---|---|---|---|
| Miner-A | 295 TH/s | 7.593 G | 343,687 | Online |
| Miner-B | 295 TH/s | 31.108 G | 338,815 | Online |
| Miner-C | 279 TH/s | 6.582 G | 301,953 | Online |
| Miner-D | 269 TH/s | 7.031 G | 287,598 | Online |
Analysis:
- All four miners stabilized between 287K and 343K Diff — a ~17% spread, which is normal for ASICs of the same model
- Best Diff for Miner-B (31.108 G) is much higher than the others — this is lottery noise, not a sign of better performance. Best Diff is cumulative and depends on luck
- Hashrate variance (~10%) is also normal day-to-day; what matters is the trend over hours, not individual minutes
6. Comparing Multiple Miners
When you run multiple identical ASICs, comparing them side-by-side is the single most reliable diagnostic technique. Differences between identical hardware almost always indicate a problem.
Example 2 — one miner underperforming:
| Worker | Hashrate | Best Diff | Current Diff | Status |
|---|---|---|---|---|
| Miner-A | 295 TH/s | 7.593 G | 343,687 | Online |
| Miner-B | 295 TH/s | 31.108 G | 338,815 | Online |
| Miner-C | 279 TH/s | 6.582 G | 301,953 | Online |
| Miner-D | 180 TH/s | 1.205 G | 115,000 | Online |
Miner-D is reporting a similar status (Online) but its Diff is nearly 3x lower than the others. Combined with a Hashrate that’s ~40% below spec, this is a clear hardware issue — likely a failed or underperforming hashboard, dirty heatsink, or thermal throttling.
7. Warning Signs — When Something is Wrong
Watch for these red flags on the dashboard:
- Diff dropping below 50% of similar miners’ Diff — likely failed hashboard or thermal throttle
- Hashrate fluctuating wildly (±30% within minutes) — power supply issue or unstable network
- Last Share growing past 60 seconds — miner is stalling or disconnected
- Status flipping Online → Warning → Online — intermittent connection or pool config error
- Best Diff stuck at startdiff (100K) for hours — miner is connecting but not actually hashing (firmware bug)
- Acceptance rate below 99% — could be high latency (wrong region), bad firmware, or hardware errors
8. What To Do When Performance is Low
When you spot an underperforming miner, work through this checklist in order:
- Compare temperatures. Open the miner’s web UI and check chip temperatures. Anything above 85°C on stock firmware = throttling. Clean fans and check ambient air temperature.
- Check power. Verify PSU output voltage and that no breaker has tripped. A failing PSU shows up first as periodic hashrate dips.
- Restart the miner. Sometimes the simplest fix. Reboot from web UI; if no improvement after 10 minutes, power-cycle.
- Test individual hashboards. Most ASIC web UIs show per-board hashrate. A failed board reduces total by ~33% (S21+ has 3 boards).
- Update firmware. BraiinsOS or LuxOS often outperform stock; if you’re on stock, consider switching for diagnostics.
- Check stratum region. A miner in Europe pointed at the US server has high latency stale shares — the Diff numbers will be deceptively low. Switch to
eu-{coin}.solofury.com. - Replace the unit. If individual board tests fail and you’ve ruled out power/thermals, a hashboard or control board may be defective. RMA if under warranty.
Next Steps
- Check your fleet on the SoloFury dashboard right now and compare Diff values across identical miners
- Read the Antminer S21+ Setup Guide if you suspect a config issue
- Use the Coin Switcher to verify you’re mining the most rewarding coin for your hashrate