Best DDR5 for local AI

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Two numbers govern a local-AI memory buy: capacity (what fits) and bandwidth (how fast it generates — see the bandwidth explainer). Everything below serves those two, in order of the decisions you'll actually make.

Pick your capacity tier

Tier	What it runs	Configuration
64GB	8–14B models generously; 32B quantized with room for context and life	2 × 32GB — the default answer
96GB	32B comfortably, 70B quantized (slowly — bandwidth, not capacity, is the complaint)	2 × 48GB — the quiet sweet spot
128GB	70B + big context, multiple models resident	2 × 64GB where supported — keeps 2-DIMM speed
192GB	Ceiling hosting for MoE/huge-context, speed-tolerant work	4 × 48GB — accept the 4-DIMM speed penalty knowingly

Price check — the default 64GB (2×32GB) DDR5-6000 CL30 kits → Price check — the sweet spot 96GB (2×48GB) DDR5-6000+ kits → Price check — capacity without the penalty 128GB (2×64GB) DDR5 kits →

Speed: the 6000–6400 CL30 sweet spot

On current mainstream platforms, DDR5-6000 to 6400 at CL30–32 is where price, stability, and the memory controller's happy zone intersect (AMD's controllers run 1:1 in this window; pushing past it buys latency compromises and training drama). Faster kits (7200–8000+) are real token-speed gains if your platform validates them — check the board's QVL before paying the premium.

Three rules that save regret

Two DIMMs, not four. Populating all four slots typically forces speeds down — the opposite of what AI workloads want. Hit capacity with bigger modules, not more of them (128 vs 192 walks the tradeoff).
Dual-rank helps. 32GB/48GB modules are typically dual-rank, which usually benchmarks a few percent ahead in bandwidth-bound work — a free win that comes with the capacity you wanted anyway.
EXPO/XMP is not optional. Out of the box, kits run JEDEC-slow; enable the profile or you paid for speed you're not getting.

When DDR6 changes this page Consumer DDR6 (2027+, timeline) roughly doubles the bandwidth column and this guide gets rewritten. Nothing you buy above is wasted in the meantime — mature-generation DRAM is the value point of the whole cycle (the price curve).