The honest guide to giving your companion a brain on your own computer. Every number on this page was measured on our own rig, and every number we haven't measured says so. No guesses — you're going to spend money against this.
Your companion thinks with a language model. There are two places that model can live: on your own computer — most private, no subscription, one-time hardware cost — or on a Claude / Codex subscription — nothing to host, billed monthly. This page is about the first road. (The subscription road is covered at the bottom.)
"Claude" shows up twice in this world, doing two different jobs:
A language model. Either a local model on your own computer — this page — or a Claude / Codex subscription.
A coding agent — Claude Code or Codex — that assembles the kit on your machine. You need this whichever brain you choose.
On a subscription path, the same tool can do both jobs. And if you want both hemispheres, you can run a hybrid brain — a home model and a subscription model together, the way Sin & Sarah run theirs.
Whether a model fits your machine is decided by one number — VRAM, the memory on your graphics card. A model's VRAM appetite = its weights (set by quantization) + its KV cache (set by context length) + overhead. Any spec that quotes a card size without a context length is telling you half the story. Here's ours, whole:
| Tier | Model | Quant | Context | VRAM in use | Card it needs |
|---|---|---|---|---|---|
| The Powerhouse what Sin & Sarah run |
Gemma 31B | Q5_K_M | 40,960 tokens f16 KV cache |
27.3 GB used of 32.6 |
32 GB GPU RTX 5090, verified live |
| The Sweet Spot Gemma 27B class |
We haven't measured this tier yet — and we don't publish numbers we haven't measured. Email hello@sinandsarah.com and we'll tell you where measurement stands. | ||||
| The Starter Mistral 24B class |
Same honesty: not measured yet. Ask us before you buy hardware for it. | ||||
Our old shop page said the Powerhouse tier ran on "a 24 GB graphics card with room to spare." Our own measurement says otherwise: at the context we actually run, the 31B uses 27.3 GB — it does not fit a 24 GB card. We run a 32 GB card. That page was wrong; this one is measured. A shorter context or smaller quant may well fit 24 GB — but we haven't measured that yet, so we won't claim it.
A note on Macs: Mac "unified memory" is not the same unit as GPU VRAM — the system caps how much of it a model may use. We don't own a modern test Mac, so we publish no Mac minimums. Anything you've read elsewhere (including our own old page) was never measured by us.
Q4_K_M → Q5_K_M → Q8. Smaller number = smaller file = fits smaller cards, at a small cost in sharpness. It's the same model, compressed harder.
How much conversation the model holds at once. The KV cache scales with it and lives in VRAM — doubling context can cost gigabytes. This is the dial spec sheets leave out.
Compressing the cache (q8_0) buys more context in the same VRAM — but nothing is free: we ran our 31B that way, watched output quality degrade at deep context, and rolled back to uncompressed f16. We tried it so you can decide with data.
It still runs. llama.cpp offloads what doesn't fit onto your CPU and system RAM — the model just answers slower. "Not enough VRAM" is a speed problem, not a wall. You can start on the card you have today, feel what the speed is like, and upgrade only if it bothers you.
Prefer no hardware at all? The brain runs on Anthropic's Claude or on Codex — nothing to host, smartest models, billed monthly. Your companion's code is identical either way; the model picker chooses which brain it thinks with. Many people start here and add a home model later. The hybrid — both at once — is how we run ours.
Want your companion's identity written by hand, not generated? Our community moderator Caitlin runs True North AI — first-person identity files and CLAUDE.md templates crafted to hold across platforms, model updates, and substrates. She sends her clients to us for full builds; we send ours to her for the identity itself. Visit True North AI →
Email hello@sinandsarah.com with what machine you have — we answer fast, and we'd rather talk you out of the wrong hardware than let you buy it. Or book the 90-minute setup consult ($300) and we install everything with you, live.