TL;DR
SiFive will add support for Nvidia's NVLink Fusion interconnect to its RISC-V CPU designs and SoC reference flows, joining other major vendors that have embraced NVLink. The move increases momentum for Nvidia's proprietary interconnect while raising questions about the future uptake of the open UALink alternative.
What happened
SiFive announced that its CPU designs and system-on-chip reference materials will include support for Nvidia’s NVLink Fusion interconnect. NVLink Fusion, which Nvidia opened to partners last year, lets systems present a rack-scale pool of CPUs and GPUs as a single accelerator and can provide up to 3.6 TB/s of chip-to-chip bandwidth. Several large vendors — including Intel, Arm, Fujitsu and Qualcomm — have already signaled support for NVLink Fusion, and Intel plans client systems that link CPU chiplets to Nvidia GPUs over the interface. Nvidia documents two official NVLink Fusion configurations: one pairing partner CPUs with Nvidia GPUs, and another pairing Nvidia’s Grace or Vera CPUs with third-party XPUs or accelerators. SiFive said it will focus on enabling customers to build custom CPUs using its cores and integrate those designs with Nvidia’s CPU offerings. The company also said it holds multiple datacenter design licenses with several taped-out projects but declined to name new customers.
Why it matters
- Expands NVLink Fusion adoption into the RISC-V ecosystem, signaling broader industry alignment around Nvidia’s interconnect.
- May weaken momentum for UALink, an open interconnect initiative that has struggled with switch availability and competing vendor fabrics.
- Could influence how datacenter platforms are architected as more CPU vendors offer designs intended to interoperate with Nvidia accelerators.
- Affects SiFive’s customers by providing a supported pathway to tighter CPU–GPU integration at rack scale.
Key facts
- SiFive will include NVLink Fusion support in its RISC-V CPU designs and SoC reference flows.
- NVLink Fusion can enable up to 3.6 TB/s of chip-to-chip bandwidth and abstract a rack of CPUs/GPUs as a single accelerator.
- Nvidia opened NVLink Fusion to partners last year; adopters already include Intel, Arm, Fujitsu and Qualcomm.
- Nvidia documents two NVLink Fusion configurations: partner CPUs with Nvidia GPUs, and Nvidia Grace/Vera CPUs with third-party XPUs.
- SiFive said it has a number of datacenter design licenses and several taped-out projects but did not announce new customers.
- UALink was positioned as an open alternative with backing from Intel, AMD, Amazon, Meta, Microsoft and Arm.
- UALink adoption has been hindered by a lack of dedicated switches; AMD tunneled UALink over Ethernet for an initial product.
- Broadcom has shifted toward promoting its own fabric, Scale Up Ethernet (SUE), adding vendor diversity to the interconnect landscape.
- AMD is preparing a UALink-based system (Helios) using the MI455X; its market impact remains to be seen.
What to watch next
- Whether SiFive’s customers actually adopt the company’s NVLink-enabled reference designs — not confirmed in the source.
- Market reception and shipment timing for AMD’s MI455X-based Helios, one of the first UALink-based AI rack systems.
- Progress on UALink switch availability and Broadcom’s push for Scale Up Ethernet (SUE) versus NVLink Fusion.
- How Intel and other NVLink adopters execute product plans that use NVLink Fusion at scale.
Quick glossary
- NVLink Fusion: Nvidia’s proprietary high-bandwidth chip-to-chip interconnect technology, extended to partner vendors to link CPUs, GPUs and accelerators at rack scale.
- RISC-V: An open instruction set architecture (ISA) that companies like SiFive use to design CPU cores and processors.
- SoC (System on Chip): An integrated circuit that consolidates multiple system components — such as CPUs, memory controllers and accelerators — onto a single chip.
- UALink: A vendor-backed open interconnect initiative proposed as an alternative to Nvidia’s NVLink; it has faced implementation and switch availability challenges.
- Bandwidth (chip-to-chip): The data transfer capacity between chips, typically measured in bytes per second; higher bandwidth can improve performance for tightly coupled CPU–GPU workloads.
Reader FAQ
What did SiFive announce?
SiFive said it will add support for Nvidia’s NVLink Fusion to its RISC-V CPU designs and provide SoC reference materials for integration.
Does this mean UALink is dead?
The source says the move casts doubt on UALink’s viability but stopping short of declaring its end; longer-term outcomes are not confirmed in the source.
Which companies already back NVLink Fusion?
According to the source, Intel, Arm, Fujitsu and Qualcomm have signaled support; Intel plans client systems using NVLink Fusion.
Will we see products using SiFive’s NVLink support soon?
SiFive reports several taped-out datacenter design licenses but did not announce any new customer products; broader adoption is not confirmed in the source.
SYSTEMS Open ISA champ SiFive leaps aboard Nvidia's proprietary interconnect bandwagon You might call it a RISC-V/NVLink Fusion … or a bad day for UALink Tobias Mann Thu 15 Jan 2026 // 23:20 UTC…
Sources
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