Intel details bitcoin mining chip

Technology News |
By Nick Flaherty

Intel has developed a 7nm chip for Bitcoin mining, detailed for the first time at the ISSCC conference this week along with a system design.

Using the BonanzaMine chip, that bitcoin mining system delivers a hash-rate of 40THash/s in a thermal design power envelope of 3600W.

A bitcoin is currently worth over €31,000, produced using the compute-intensive SHA256 double hash process as proof-of-work. The one-way property of SHA256 requires a brute force search by sweeping a 32b random input value called nonce. The 232 nonce space search results in energy-intensive pool operations distributed on high-throughput mining systems, executing parallel nonce searches.

This has led to farms of GPUs or ASICs using low cost electricity to generate hash chain to earn a share of the bitcoins as they are released in blocks.

Each BonanzaMine ASIC is composed of 258 mining engines that are programmed through anon-die 8b slow-speed bus to compute parallel SHA256 double hashes. Mining engines contribute to 90% of die area and operate at an ultra[1]low voltage of 355mV. A notch region at the bottom of the die contains high-voltage (750mV) circuits, including PLL, voltage/thermal sensors, and UART/JTAG control logic to handle I/O to the engines through voltage level shifters.

The BonanzaMine system is a self-contained unit composed of 4 hash boards, an Intel FPGA-based control unit, programmable power supply and four fans, delivering a hash-rate of 40THash/s under a thermal design power envelope of 3600W.

Each hash board houses 75 mining ASICs organized as three 25-deep voltage stacks with ganged stack-voltages, along with a microcontroller that manages power-on and thermal/stack-voltage monitoring. The ASICs are daisy-chained with a 10Mb/s UART serial link that delivers mining payloads and outputs to/from the control unit.

The control unit hosts the mining daemon running on an ARM Cortex core to deploy mining workloads, program on-die PLLs for frequency-control and verify hash results to/from the individual ASICs over the UART link. The control unit also communicates with mining pools over an Ethernet link.

Built in a 7nm process, the BonanzaMine die measures 14.16mm2 and is packaged in 7×7.5mm2 exposed die molded FCLGA 132-ball package (Fig. 21.3.7). ASICs operate at 1.35 to 1.6GHz at 355mV, 75°C, generating 116 to 137GHash/s with average power consumption of 7.5W, resulting in energy-efficiency of 55J/THash.

System firmware uses periodic test patterns to identify and turn off failing engines at runtime, enabling 15% performance boost by operating the remaining good engines at a higher frequency (1.6GHz). The mining system takes advantage of this capability to operate in a variable energy-cost scenario by switching between high-performance, balanced and power saving modes with energy-efficiencies ranging from 54 to 60J/THas

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