SiFive Inc., a startup that sells chip designs based on the open-source RISC-V architecture, has raised $400 million in funding at a $3.65 billion valuation.

Atreides Management led the Series G round. SiFive said in today’s funding announcement that Nvidia Corp., enterprise technology investor Apollo and other institutional backers contributed as well. The company’s total outside funding now exceeds $760 million.

Central processing units crunch data using a library of prepackaged computing operations. Some of those operations perform simple mathematical calculations. Others carry out more specialized tasks such as moving data between different memory addresses. A CPU’s library of computing operations is known as its instruction set architecture, or ISA.

SiFive was founded in 2015 by the creators of RISC-V, a popular open-source ISA. It includes not only a library of prepackaged computing operations, or instructions, but also supporting components such as memory management modules. 

RSIC-V can significantly reduce the amount of time needed to develop a custom CPU. However, the task is still highly resource-intensive and requires specialized skills. SiFive sells ready-to-use RISC-V processor designs that customers can use to speed up their semiconductor projects.

The company’s product portfolio includes more than a dozen CPU blueprints. Some include reliability features that make them suitable for use in vehicles, while others are geared toward battery-powered connected devices. SiFive also offers a growing lineup of data center chips.

The company’s most advanced design, the Performance P870-D, makes it possible to build server CPUs with up to 256 cores. It includes a module called an interrupt controller that optimizes the order in which calculations are carried out based on their importance. Data protection accelerators speed up tasks such as encrypting network traffic.

The Performance P870-D includes a so-called cluster accelerator port that can be used to connect it to another processor. A cloud provider, for example, could integrate the CPU with a custom graphics card. The Performance P870-D also works with SiFive’s own SiFive Intelligence line of machine learning accelerators.

The company introduced its flagship AI chip last September. The XM Gen 2 is optimized to process matrices, the mathematical objects in which AI models keep information. XM Gen 2 makes it possible to assemble an accelerator from multiple four-core processing clusters that can each perform 16 trillion calculations per second.

SiFive’s customer base reportedly includes several of the world’s largest tech firms. Those customers have used its blueprints to create more than 500 chip designs.

“Hyperscale customers have made it very clear that it is time to accelerate the availability of open standard alternatives for the data center,” said SiFive Chief Executive Patrick Little. “Their consistent ask is for customizable CPU solutions in IP form, that will enable them to meaningfully differentiate their data center compute solutions.”

SiFive will use the proceeds from its funding round to accelerate its engineering efforts. The company plans to develop new RISV-C and AI products for data centers. 

Photo: SiFive