At first there were only CPUs, then came GPUs for Bitcoin mining. In 2013, a powerful ASIC entered the market, and with it came the shoebox form factor, which became the symbol of Bitcoin mining.
So what lies ahead? Will the shoebox shape remain the standard for Bitcoin ASIC mining? Or will a different form factor, more reminiscent of traditional data center servers, be favored?
ASIC manufacturers are increasingly betting on the latter – or at least that hydro-cooled server rack designs will become a major part of Bitcoin mining fleets. What’s more, they’re starting to use “direct-to-chip” cooling to improve efficiency.
The new AH3880 from Auradine, released in March 2025.
Last September, Bitmain unveiled its U3S21EXPH (a complicated name, huh?) in collaboration with Hut 8. The U3's design means that one unit takes up three rack spaces. MicroBT soon followed up with the M63 Hydro series, as well as Bitdeer's Sealminer A2 Hydro.
Following suit, Auradine introduced its AH3880 rackmount server model in March this year. Its U2 design, which takes up two server slots, is slightly smaller but delivers a higher hashrate per unit of space – 600 TH/s (or 300 TH/s per slot), compared to Bitmain’s 860 TH/s (286.66 TH/s per slot).
Shoe box
So what does the move away from the traditional shoebox mean? For Auradine, it has to do with customer needs.
“[Our new model] is based on a lot of feedback from our mining customers… we engaged with miners throughout the design process,” said Sanjay Gupta, CSO of Auradine, speaking about the latest Mining Pod. “They indicated that they were looking for a quality hydronic miner.”
As part of the partnership with Bitmain on the U3S21EXPH project, “Hut 8 played a significant role in developing custom infrastructure, particularly the U form factor, which is compatible with HPC-style architecture,” Sue Ennis, head of investor relations at Hut 8, said last September. (Details on high-performance computing will be discussed later.)
The advantage of the ASIC server rack is standardization. Bitcoin miners are increasingly integrated into the traditional data center industry, and according to data center developer Cyrus One, the industry could reach 40% liquid crystal cooling adoption by 2026.
If miners adopt this design, they could theoretically optimize their supply chains by switching to server designs that are becoming standard in large data centers.
This could make it easier to build and repair Bitcoin miners. It could also make mining companies more flexible if they want to move from Bitcoin mining to other forms of computing.
Introduction to AI and HPC
As with much of the mining news today, the specter of AI looms in the background.
If miners build their data centers with traditional server rack designs, they will have fewer issues if they want to adapt those sites for AI and HPC workloads. Of course, they will still have to upgrade their network and electrical infrastructure, but server racks will provide a foundation for AI/HPC services that requires fewer changes than traditional Bitcoin mining. As Ennis noted, “the U form factor… is compatible with HPC-style architecture.”
Supporting this, Gupta stated in our interview with Mining Pod that “[the U form factor] has been used in AI data centers. It’s easy to configure. It has a high [power density]… [it’s] also very relevant for AI data centers, and we’re looking at a joint strategy between AI for HPC and Bitcoin mining. So the U form factor is perfect for that.”
Who buys this?
It probably goes without saying that the Bitcoin mining server rack form factor is still in its early stages of development, and while there is hope that such a design could become dominant, there are no guarantees of that.
First and foremost, Bitcoin miners will have to not only rethink the internal workings of their mines, but also completely redesign their electrical infrastructure (which is unlikely to happen at existing sites).
Brad Cuddy of Cholla, a water-cooled ASIC miner, told Blockspace last September that he was “excited to see the move from the shoebox design to the [server rack] form factor.” However, he noted that the U3S21EXPH’s voltage range is incompatible with certain electrical infrastructure used by miners with other Bitmain models.
“The limited range of 380 to 415 volts reduces its compatibility for retrofitting. I would like to see the voltage range reach 480 volts to provide greater compatibility with current infrastructure deployments,” he said.
It is therefore likely that we will see the integration of these blocks on new platforms. Hut 8 is taking this approach, planning to host 15 EH/s U3S21EXPH blocks from Bitmain (
Source: cryptonews.net
