Best of Jeff Geerling — December 2025

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   Jeff Geerling·24w

   The RAM Shortage Comes for Us All

   RAM prices have skyrocketed dramatically in recent months, with some DDR5 kits jumping from $209 to $650. The shortage is driven by memory manufacturers prioritizing AI datacenter production over consumer markets, forcing companies like Raspberry Pi to raise prices and Micron to exit the consumer memory business entirely. Small vendors face even worse price increases, with some memory modules tripling or quadrupling in cost. Unlike previous shortages, the specialized nature of AI hardware means there won't be a flood of cheap consumer-compatible parts when the bubble bursts. PC builders, SBC enthusiasts, and smaller manufacturers are being hit hardest, with the situation expected to continue affecting any product containing memory.

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   Article

   Jeff Geerling·22w

   1.5 TB of VRAM on Mac Studio - RDMA over Thunderbolt 5

   Testing RDMA over Thunderbolt 5 on a four-Mac Studio cluster with 1.5 TB unified memory shows significant performance gains for running massive AI models. The M3 Ultra Mac Studio outperforms comparable systems from Nvidia and AMD in CPU, AI inference, and power efficiency benchmarks. RDMA support in Exo 1.0 enables linear performance scaling across nodes, achieving 30+ tokens/second on trillion-parameter models. However, limitations include Thunderbolt 5's four-node maximum, macOS cluster management challenges, stability issues with prerelease software, and lack of standard networking options like QSFP for larger deployments.

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