Hardware & Storage
Thunderbolt 4/5, NVMe enclosures, DRAM vs DRAMless, and external storage for local models.
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Thunderbolt 4 & 5 on Mac mini
Mac mini M2/M2 Pro have Thunderbolt 4 (40 Gb/s, ~5 GB/s). M4 Pro models have Thunderbolt 5 (120 Gb/s). A good TB4/USB4 NVMe enclosure can outpace the base 256GB internal SSD (many report 3,500+ MB/s external vs ~2,500 MB/s internal). For Ollama and model files, that’s more than enough.
- TB4/USB4 enclosures (40 Gbps): Acasis, Qwiizlab, OWC, Orico, WavLink, Satechi. Pair with an NVMe (Samsung 990 Pro, WD SN770, etc.). Enclosures with a fan help under sustained load.
- Daisy chaining: TB4 hubs support multiple devices; you can run enclosure + display + Ethernet off one port.
- Use case: Put the BRAIN’s Ollama model library on an external TB4 NVMe to free internal space and get fast load times.
DRAM vs DRAMless SSDs
When buying an SSD (internal or external), you’ll see “DRAM” or “DRAMless.” Here’s what matters for running local models and general use.
| Type | How it works | Best for |
|---|---|---|
| DRAM SSD | Has onboard DRAM for mapping table and write buffering. More consistent speed and longevity. | Primary/boot drives, heavy writes, when you want maximum reliability. Slightly higher cost. |
| DRAMless SSD | Uses host RAM (HMB) instead of onboard DRAM. Cheaper, lower power; can be slower under mixed workloads. | Budget external storage, mostly reads (e.g. model files). Fine for Ollama model storage if you’re cost-conscious. |
Recommendation: For an external drive that mainly holds model files (read-heavy), DRAMless is acceptable and saves money. For a drive you also use for lots of writes or as a primary volume, prefer DRAM.
External drives for models
- Thunderbolt 4 / USB4 NVMe enclosures — 40 Gbps; use your own NVMe (DRAM or DRAMless). Best performance for Mac mini. See Thunderbolt section above.
- Pre-built portables — Many are DRAMless. Check reviews; fine for model storage if price is priority.
- Capacity — Plan for 20GB–50GB+ per model if you keep several. 500GB–1TB is a comfortable range.
Budget-friendly options
For “good enough” model storage: DRAMless NVMe in a USB-C enclosure, or a sale-price portable SSD. For “I want it to last and stay fast”: choose a DRAM-equipped NVMe (e.g. Samsung 970/980 Pro, WD Black) in an enclosure.