The Nervos Network (CKB) is one of the few modern blockchains that still runs on Proof-of-Work (PoW). Instead of abandoning mining for Proof-of-Stake, Nervos doubles down on security through Eaglesong, its custom PoW algorithm. Eaglesong was designed to be ASIC-friendly, making specialized hardware the backbone of the ecosystem.

For miners, this opened the door to high-performance rigs such as the Bitmain Antminer K7, as well as smaller competitors like Goldshell. But as we’ve seen at Captain Mining, not all ASICs are created equal. While the K7 promised industry-leading performance, its real-world reliability left many operators disappointed, especially when deployed at scale in hosting environments.

This article breaks down Nervos mining, the hardware landscape, and what miners have learned from the K7’s rise — and its pitfalls.

Nervos Mining and the Eaglesong Algorithm

Nervos uses Eaglesong, a simple hash function optimized for ASIC development. When CKB launched in 2019, the team wanted a PoW algorithm that wouldn’t be dominated by GPUs forever. By 2020, ASIC manufacturers had already delivered the first dedicated miners.

Eaglesong makes Nervos unique because:

• It allows relatively fast ASIC innovation.

• It avoids the endless GPU vs ASIC wars seen on coins like Ethereum (before ETH switched to Proof-of-Stake).

• It anchors Nervos as a PoW chain with predictable mining economics.

From the beginning, Nervos has been ASIC territory — and today, machines like the Antminer K7 dominate network hashrate.

The Antminer K7: Specs and Expectations

When Bitmain launched the Antminer K7 in early 2023, it was hailed as the king of Eaglesong. On paper, its specs were unmatched:

• Hashrate: 63.5 TH/s

• Power consumption: 3080 W

• Efficiency: ~48.5 J/TH

• Cooling: 4 high-speed fans

Compared to earlier Goldshell models (like the CK6 at 19.3 TH/s, or CK-Lite at 6.3 TH/s), the K7 was in another league. It promised to triple or quadruple hashrate at a better efficiency per joule. For large-scale miners, it looked like the perfect machine to secure Nervos and generate consistent profit.

Real-World Issues with the K7

At Captain Mining, we hosted several Antminer K7 units. While their raw performance was undeniable, our technicians quickly noticed a pattern of failures and instability.

Overheating and Shutdowns

With over 3 kW of power consumption, the K7 generates immense heat. In practice, many units would overheat in environments above 25°C. Even small ventilation issues caused automatic shutdowns. In hosting centers, keeping these machines cool required far more infrastructure than comparable ASICs.

Circuit and Soldering Problems

One of our technicians identified a critical weakness: poor soldering on the circuit boards. This meant chips were more prone to detaching under thermal stress. When units ran hot for extended periods, hashboards would fail entirely. Some K7s would start dropping chips within months of operation.

This is a recurring issue with ASICs built for newer algorithms. Manufacturers rush to deliver high-performance models, sometimes at the cost of long-term durability. Unfortunately, the K7 became a case study in this trade-off: incredible hashrate, but fragile hardware.

Frequent Maintenance

In daily operation, we observed:

• Fans failing under continuous high RPM.

• Hashboards needing frequent resets or reflows.

• Entire units requiring RMA within the first year.

For a hosting provider, this made the K7 one of the most labor-intensive miners we’ve managed.

Goldshell and Other ASICs

Goldshell also manufactures ASICs for Nervos, such as the CK6 (19.3 TH/s, 3300 W) and CK-Lite (6.3 TH/s, 1200 W). While these machines are less powerful than the K7, they have a reputation for being more stable in home and small-scale setups.

That said, information on Goldshell performance in long-term Nervos mining is sparse. Few large farms deploy them, so most insights come from individual miners rather than industrial-scale operators. By contrast, the K7 has been battle-tested in hosting environments — and its weaknesses are better documented.

Lessons from the K7 at Captain Mining

Our experience with the K7 highlights a key lesson for miners: new does not always mean better. When a new ASIC launches on a fresh algorithm, it often offers unmatched profitability in the short term. But hardware flaws can erode those gains quickly.

In the case of the K7:

• Strengths: Industry-leading hashrate, excellent efficiency, dominance on Eaglesong.

• Weaknesses: Overheating, weak soldering, high failure rates, and heavy maintenance.

For miners who deployed early, profits may have offset these issues. But for long-term operators and hosting providers, reliability costs were significant.

The Future of CKB Mining

Nervos remains one of the few PoW blockchains designed with ASICs in mind. As long as Eaglesong is the mining algorithm, ASIC innovation will continue. We expect new generations of miners from Bitmain, Goldshell, or other manufacturers — and with them, the same trade-offs between power and durability.

At Captain Mining, we believe miners should weigh not just efficiency and hashrate, but also reliability. The K7’s history shows that cutting-edge specs can hide design flaws that only appear months into real-world use.

For the long-term sustainability of CKB mining, the industry will need ASICs that balance raw performance with better build quality. Until then, miners must prepare for higher maintenance costs and choose carefully between available models.

Conclusion

The Antminer K7 will be remembered as both a milestone and a warning in Nervos mining. It delivered unmatched Eaglesong performance, but at the cost of stability and durability. Hosting providers like Captain Mining saw firsthand how fragile the units could be under heat and stress, with technicians pointing to poor soldering and circuit issues as root causes.

Goldshell ASICs offer alternatives, but their performance is modest and less documented at scale. For now, Nervos mining remains a space of opportunity and risk — where hardware innovation runs fast, but reliability often lags behind.

For miners, the lesson is clear: don’t just chase the biggest numbers. Chase sustainability.