Mac Studio (M5 Ultra) with 256 GB of RAM review: a dream machine to run local AI agents and a massive leap over M3 Ultra for prompt processing and generation

Local AI agents now perform with speeds that make them a practical alternative to cloud services for many users.

Apple's M5 Ultra Mac Studio, equipped with 256 GB of RAM, is proving to be a powerful machine for running local AI agents, significantly outperforming its predecessor, the M3 Ultra. Testing has shown the M5 Ultra offers substantial improvements in prompt processing and text generation speeds for local AI models. Federico Viticci of MacStories has adopted the M5 Ultra Mac Studio as his primary device for AI tasks, replacing cloud-based solutions due to its performance, cost-effectiveness, and privacy benefits. The M5 Ultra features a new quad-die architecture, an 80-core GPU with enhanced AI capabilities, and 1.2 TB/s memory bandwidth, a 50% increase over the M3 Ultra. This hardware upgrade results in local AI agents responding approximately 70% faster and maintaining high speeds with large context windows, making complex AI workflows practical on personal hardware. The reviewer highlights its advantage over a high-end gaming PC like an RTX 5090 in terms of size, heat, and noise, despite the PC's memory bandwidth edge.

The M5 Ultra Mac Studio's advancements in GPU compute and memory bandwidth—specifically a 4.5x increase in AI compute and a 50% boost in memory bandwidth to 1.2 TB/s—enable local AI models to achieve speeds that rival or surpass cloud-based alternatives for many tasks. This leap means that users can now run complex AI agents, like those used for research and writing assistance, entirely on their own hardware without significant performance compromises or ongoing cloud subscription costs.

This development signals a potential shift towards greater decentralization in AI workflows, empowering individuals and smaller organizations with powerful AI capabilities previously accessible only through expensive cloud infrastructure. The ability to process prompts and generate responses rapidly on local hardware also makes sophisticated agentic loops, involving tool calls and multi-turn conversations, a viable and efficient option for personal productivity and creative projects.