The emerging virtual money economy has firms racing to market with bitcoin mining chips, and in just eight months, start-up CoinTerrain developed a 28nm ASIC that pushes the envelope of power density, and shipped a system that equips four of them.

Bitcoin is the most high profile of several emerging digital exchanges founded on a set of mathematical formulas and open source software released in 2009. Its de-centralized economy is based on bitcoin mining, essentially clearing transactions that use an increasingly complex set of cryptographic puzzles based on the SHA-256 hashing algorithm.

The first bitcoin mining systems to crack the code of a puzzle get rewarded, sometimes to the tune of millions in virtual currency. Initially participants used standard PCs for bitcoin mining. But as transactions became increasingly complex the community moved to GPU and FPGA accelerators and—since January 2013—to ASICs.

"The race is to build the highest performance yet most power efficient platform based on ASICs," said Javed Barkatullah, CoinTerra's lead ASIC designer in a talk at the Hot Chips event here.

CoinTerra's Goldstrike-1 chip packs 120 hash engines into a single chip made by Globalfoundries. The start-up puts four chips in a 37.5mm2 FCBGA package and two packages on each of two 250W boards in a single system.

The chips, which use no memory, are aimed at super-fast logic execution and thus guzzle power and generate lots of heat. The system uses off-the-shelf automotive cables to deliver 84A of current to each chip. Liquid cooling with glycol antifreeze typically used by computer game enthusiasts keeps the chips cool.

The "very high toggle rates of 80 per cent on average" for the bitcoin algorithm drives the need for high power and liquid cooling, said Barkatullah.

Indeed, the puzzles—which must be completed within ten minutes—are so complex "no single machine is guaranteed to solve one in its life time," he said.

Bitcoin miners now form collaborative computing pools and share revenues they win based on the percentage of compute power each member contributes. The overall bitcoin network is estimated to consume about 150MW a day.

In a sign of the speed of the bitcoin performance race, the TerraMiner system launched in January at $6,000 but now costs just $3,000. The price decline relates to the ever-increasing complexity of the bitcoin hash puzzles.

CoinTerra employs just ten ASIC designers. They were able to finish the project so quickly because the team consists solely of veterans with at least 25 years' experience, said Barkatullah, a former chip designer at Intel and Nvidia. They outsourced much of the implementation work, but contractors disappointed Barkatullah because they did not work fast enough, he said in an interview

By: DocMemory
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