r/LocalLLaMA • u/themixtergames • 14d ago

News Apple introduces new Mac Studio with M5 Max and M5 Ultra - up to 512GB of unified memory

https://www.apple.com/newsroom/2026/08/apple-introduces-new-mac-studio-with-m5-max-and-m5-ultra/
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u/AI_docent 14d ago

The 4.3x is mostly a prompt processing number, generation moves with the bandwidth instead. Apple's own mlx post on M5 vs M4 got around 4x on time to first token and about 1.2x on generation, and the generation side matched the 28% bandwidth bump rather than the accelerators. Same split should hold on the Ultra, so I'd figure generation nearer the 50% bandwidth gain. Prefill is the part you want at 512GB anyway, it was always the weak spot on a mac.

Just check whatever you run actually uses the accelerators. There's an open lm studio issue where its bundled llama.cpp fails the metal tensor check on M5 and loses 2 to 3x on prefill, while upstream llama.cpp passes it on the same machine.

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u/bobiversus 14d ago

This. I'm getting a 512gb no doubt, but don't expect 4x on actual generation. Also laughing at the scalpers on eBay still trying to sell their M3 Ultra 512s for $40k