Min VRAM needed
1.4 GB
Weights: 0.4 GB
KV cache: 0.4 GB
Overhead: 0.5 GB
Buy memory capacity first
For local LLMs, the first question is whether model weights, KV cache, runtime buffers, and the operating system fit. GPU marketing metrics do not rescue a profile that runs out of memory at the intended context. For Hermes, budget for at least a 64K context, not merely a short chat prompt.
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Best low-maintenance appliance: Mac mini M5 Pro 48/64 GB
Apple's current Mac mini specification lists 24 GB unified memory on the base M5 Pro and configurable 48 GB or 64 GB tiers, all with 307 GB/s memory bandwidth. A Mac mini is compact, quiet, and lets the GPU use unified memory. The tradeoff is fixed memory and no supported eGPU upgrade. For a long-lived local-agent appliance, choose the required memory on day one; external storage can expand later, memory cannot.
Best upgradeable compact path: OCuLink mini PC
A Windows/Linux mini PC with native OCuLink can attach a desktop GPU over PCIe 4.0 x4. At verification, Minisforum's AI X1 Pro-470 offered OCuLink and up to 128 GB DDR5, while its DEG1 dock exposed PCIe 4.0 x4 and accepted ATX/SFX power supplies. This path keeps the computer small while letting the expensive GPU change later. Product prices and stock are volatile; recheck the official store before buying.
Do not combine the two strategies
OCuLink/Thunderbolt eGPU advice applies to compatible Windows or Linux PCs, not Apple-silicon Macs. Apple's eGPU documentation explicitly requires an Intel Mac. An M-series Mac's Thunderbolt 5 bandwidth is useful for storage and displays, but it does not add supported external GPU compute.
NVIDIA capacity tiers
NVIDIA's official current comparison lists 16 GB for RTX 5060 Ti (one variant), RTX 5070 Ti, and RTX 5080, and 32 GB for RTX 5090. Sixteen-gigabyte cards are good 7B–14B accelerators but are not a comfortable 27B-plus, 64K agent tier. RTX 5090's 32 GB makes it the cleanest single consumer NVIDIA card for larger quantized profiles, but actual board prices and power requirements vary widely.
Our measured evidence
A CPU-only 16 GiB Ubuntu VM ran Qwen 3.5 9B with Hermes at 64K, but the agent response took roughly four minutes. A 36 GB M4 Max Mac ran verified Qwen 3.8 27B MLX direct inference in 14.9 seconds, yet the full Hermes 64K call exceeded seven minutes. These results show why both capacity and harness-level testing matter; they are not cross-vendor benchmarks.
Recommended purchase ladder
Use existing hardware first with the 9B profile. For a quiet new appliance, choose a 48/64 GB Mac mini M5 Pro; choose an M6 configuration only when its 16–32 GB ceiling matches the tested model profile. For CUDA, model experimentation, and future GPU upgrades, choose an OCuLink mini PC plus a 16 GB GPU initially, then move to a 32 GB card only when a tested profile needs it. Choose Mac Studio M5 Max or M5 Ultra when unified-memory capacity above the Mac mini tier matters more than CUDA compatibility.
Before spending money
Check the exact model profile, desired context, physical GPU dimensions, dock power supply, OCuLink cable/port compatibility, OS driver support, seller return policy, and current official price. We intentionally do not publish retailer-derived token-per-second promises. A system becomes recommended only after its full runtime + model + Hermes acceptance profile passes.