Anthropic says Claude Mythos ported Claude to AMD MI355X GPUs in about three days
In brief
- Claude Mythos ported Claude to AMD's MI355X GPUs in about three days, Anthropic said.
- Human involvement was minimal, Anthropic said, according to Crypto Briefing.
- Moving a large AI model to new hardware usually takes months of engineering, Crypto Briefing said.
- AMD and Anthropic announced a partnership on July 22, 2026, including up to $5 billion in AMD equity.
How the port worked, per Anthropic
An Anthropic engineer reportedly connected Claude to the new AMD hardware and told it to begin, according to Crypto Briefing. The report doesn't name the engineer. From there, the model handled the software migration and tuned performance across roughly three days.
Anthropic's research describes steadily improving performance curves, achieved without ongoing human intervention. It's worth being precise here (the company characterized the human role as minimal, not absent). Those characterizations come from Anthropic, as relayed by Crypto Briefing.
The comparison point matters. Crypto Briefing noted that moving a large AI model onto new hardware usually takes months of engineering.
Three days is a very different number.
The MI355X hardware
AMD's MI355X is built on the company's CDNA 4 architecture. It carries 288 GB of HBM3E memory and 8 TB/s of bandwidth, with up to 10 PFLOPS of peak performance, according to the report.
Where Mythos and the AMD deal fit
Anthropic unveiled Claude Mythos 5.2 on November 9, 2026, describing it as its most advanced model yet in cybersecurity and life sciences. Access runs exclusively through vetted programs, and Mythos-class models have shown significant capabilities in autonomous cybersecurity tasks, Crypto Briefing reported. Pricing is set at $8 per million input tokens and $40 per million output tokens; a fast mode doubles that cost.
There's a larger commercial backdrop, too. On July 22, 2026, AMD and Anthropic announced a strategic partnership built around AMD's Instinct MI450-series GPUs, as reported. Under that agreement, Anthropic committed to using up to 2 GW of MI450-series GPUs in AMD's Helios rack-scale systems, with deployment planned to begin in the first half of 2027. AMD pledged an equity investment of up to $5 billion in Anthropic.
The deal also included a plan to use Claude to improve ROCm, AMD's software stack for running AI workloads on its chips.
Frequently asked questions
How long did Anthropic say it took Claude Mythos to get Claude running on AMD GPUs?
Anthropic said Claude Mythos got Claude running on AMD's MI355X GPUs in about three days with minimal human help, according to Crypto Briefing. The model reportedly handled the software migration and tuned performance over that period.
What are the specs of AMD's MI355X GPU?
The MI355X is built on AMD's CDNA 4 architecture. It carries 288 GB of HBM3E memory and 8 TB/s of bandwidth, with up to 10 PFLOPS of peak performance, according to Crypto Briefing.
What did the July 2026 AMD and Anthropic partnership include?
Announced on July 22, 2026, the partnership centers on AMD's Instinct MI450-series GPUs. Anthropic committed to using up to 2 GW of them in AMD's Helios rack-scale systems, with deployment planned for the first half of 2027. AMD pledged up to $5 billion in equity investment, and the deal includes a plan to use Claude to improve AMD's ROCm software stack.
