npcvram

Will your PC run Skyrim with AI NPCs?

Game + local LLM + AI voices on one GPU — or is the cloud cheaper? Pick your GPU, mod and model. Get an answer in 30 seconds.

Check my GPU

Built on published numbers from Mantella, CHIM, SkyrimNet & model files on Hugging Face. Estimates ±1–2 GB.

LLM backends: OpenRouter, OpenAI, KoboldCpp, text-generation-webui, LM Studio, Ollama, any OpenAI-compatible

Estimated VRAM

11.2 / 12 GB

LOCAL_TIGHT

It fits, but with under 10 % headroom. Lower textures/resolution, use Q4, or move voice to the CPU.

4.0
4.9
1.1
90% · 10.8 GB
Game 4.00LLM weights 4.92KV cache 1.07LLM runtime 0.50TTS (voice) 0.00STT 0.00OS reserve 0.70

What to do

  1. Lower the context to 4k tokens — saves ~0.53 GB of KV cache.
  2. A smaller model fits: Qwen2.5 7B Instruct at Q4_K_M (~10.35 GB total).
  3. Run the LLM in the cloud (OpenRouter, Player2, Mistral free tier) and keep the game + voice local — frees ~6.49 GB. CHIM's docs say ~$5 on OpenRouter goes a long way.
Report your real VRAMEstimate ±1–2 GB.

Get the full calculator — real benchmarks, more games, cloud cost per hour.

More games, measured benchmarks, cloud price per hour, a shareable link to your rig.

By joining you agree that we e-mail you about npcvram (no spam, unsubscribe anytime). Privacy

What fits on 8, 12, 16 and 24 GB GPUs?

On 8 GB modded Skyrim leaves no room for a local LLM — run it in the cloud; 12 GB fits a 7B model with CPU voice; an 8B model plus GPU voices (XTTS + Whisper) needs 24 GB. Scenario: Skyrim SE at 1080p with 2K textures (~4 GB), Q4_K_M, 8k context, 10 % headroom; models from our list (3B–12B).

VRAMUsable (90 %)Largest local LLM · Piper on CPU, no STTLargest local LLM · XTTS + Whisper base on GPULlama 3.1 8B + XTTS + Whisper (16.2 GB)
8 GB7.2 GBLLM in the cloud (game + voice ~4.7 GB)Voice on CPU + cloud LLM✕ CPU_VOICE_CLOUD_LLM
12 GB10.8 GBQwen2.5 7B Instruct (~10.3 GB)LLM in the cloud (game + voice ~9.7 GB)◐ HYBRID
16 GB14.4 GBMistral Nemo 12B (~14.0 GB)Qwen3 4B (~13.9 GB)◐ HYBRID
24 GB21.6 GBMistral Nemo 12B (~14.0 GB)Mistral Nemo 12B (~19.0 GB)✓ LOCAL_OK

How much VRAM do Mantella / CHIM need?

With a local LLM and GPU voices, plan on roughly 16 GB for modded Skyrim: our estimate for Skyrim with 2K textures + Llama 3.1 8B (Q4_K_M, 8k context) + XTTS + Whisper base is 16.2 GB.

Mantella's docs ask for at least 6 GB of free VRAM, with 12–15 GB as the optimum. CHIM's docs recommend an RTX 3090 or better to run Skyrim, the LLM and TTS on one PC; otherwise use a second PC or the cloud.

With the default stacks (Mantella: Piper on the CPU + OpenRouter; CHIM: OpenRouter + Chatterbox or Pocket TTS) the LLM costs no VRAM at all — only the voice model and the game do.

Local LLM vs OpenRouter for Skyrim

A local 8B model costs about 6.5 GB of VRAM (Llama 3.1 8B Q4_K_M at 8k context, incl. KV cache and runtime), while OpenRouter costs 0 GB VRAM but money per message.

OpenRouter is pay-as-you-go: free models are limited to about 50 requests/day, about 1,000/day after a $10 deposit. CHIM's docs say $5 goes a long way; SkyrimNet guides suggest ~$10 to start (secondary sources, read 2026-10-23).

Player2 is a free local/AI app supported by CHIM, AI Influence (Bannerlord) and RimTalk. If the game + LLM don't fit, our verdict is HYBRID: LLM in the cloud, voice local.

XTTS vs Piper VRAM

XTTS v2 needs about 4 GB of VRAM on an NVIDIA (CUDA) GPU, while Piper runs on the CPU with 0 GB VRAM and ~0.1 GB RAM.

XTTS sounds better and can clone voices; Piper is more monotone. Pocket TTS (Kyutai) is another CPU option with good quality and voice cloning. Chatterbox (~6 GB) and Kokoro (~2 GB) sit in between.

CPU voices cost no VRAM, but they use CPU time, which can lower FPS in CPU-bound games like Skyrim and Fallout 4. AMD and Intel GPU owners can't run XTTS on the GPU.

How accurate is this calculator?

Treat every number as an estimate within ±1–2 GB: game VRAM varies a lot by modlist, and our KV-cache figure is an upper bound.

The formula reproduces the AI NPC Cyberpunk mod's measured numbers for its lite local pack within 1 GB, but over-estimates its standard pack by ~2.7 GB (likely CPU offload) — so it errs on the safe side. Report your real VRAM to help us calibrate.

Methodology & sources

Total VRAM = game preset + [GGUF file + KV cache + 0.5 GB runtime] (local LLM only) + GPU TTS + GPU STT + 0.7 GB OS reserve, compared with 90 % of your GPU's VRAM.

KV cache (fp16) = 2 × layers × KV heads × head dim × 2 bytes × context tokens estimate. It is an upper bound: grouped-query attention is included, Gemma's sliding window is not. Runtime overhead 0.5 GB (CUDA context + llama.cpp compute buffer) estimate, OS reserve 0.7 GB (Windows desktop, browser, Discord) estimate, 10 % headroom (Step Mods forum: keep 10–15 % VRAM free) secondary source.

Verdicts: LOCAL_OK total ≤ 90 % · LOCAL_TIGHT 90–100 % · HYBRID game + GPU voice fit, LLM doesn't · CPU_VOICE_CLOUD_LLM not even GPU voice fits. Partial CPU offload of LLM layers also works, but much slower.

Known limits: game VRAM is a community/benchmark average and modlists differ by several GB; XTTS and some TTS need NVIDIA CUDA; CPU TTS can lower FPS in CPU-bound games. Calibration: the AI NPC Cyberpunk mod (Nexus 35436) publishes measured totals; the lite pack matches within 1 GB, the standard pack is over-estimated by ~2.7 GB.

Data sources (all read 2026-10-23)

ItemValueSource
Skyrim Special/Anniversary Edition2.2 / 4 / 5 / 7 GBstepmodifications.org forum 13153 (vanilla 'a bit over 2 GB'); r/skyrimmods 7qzd5c (2K ~4 GB, 4K textures 6–8 GB) secondary source · read 2026-10-23
Skyrim VR5 / 8 GBderived: VR renders ~2× 1080p resolution; to be verified estimate · read 2026-10-23
Fallout 4 (Next-Gen)3.5 / 4 / 5 / 6 GBen.gamegpu.com/test-gpu/rpgrolevye/fallout-4-next-gen-update-test-gpu-cpu (3–4/4/5 GB); pcoptimizedsettings.com (<6 GB even with HD pack at 4K) verified · read 2026-10-23
Fallout 4 VR6 GBnot measured estimate · read 2026-10-23
Cyberpunk 2077 (2.31)6.5 / 9.5 / 12 GBnexusmods.com/cyberpunk2077/mods/35436 (mod author: 6–7 / 9–10 / 12+ GB) verified · read 2026-10-23
Mount & Blade II: Bannerlord3.3 / 3.8 / 4.7 GBen.gamegpu.com Bannerlord 1.5.8 a 1.0.0.3729 (VRAM tables) verified · read 2026-10-23
RimWorld1 GB2D game, not measured; to be verified estimate · read 2026-10-23
Stardew Valley0.5 GB2D game; Steam min. spec 256 MB VRAM (not re-checked) estimate · read 2026-10-23
Minecraft Java1 / 3 GBnot measured; shader packs need much more estimate · read 2026-10-23
LLMs (12, 3B–12B)Llama 3.2 3B Instruct, Qwen2.5 3B Instruct, Phi-3.5 mini (3.8B), Gemma 3 4B, Qwen3 4B, Mistral 7B Instruct v0.3, Qwen2.5 7B Instruct, Llama 3.1 8B Instruct, Qwen3 8B, Gemma 2 9B, Mistral Nemo 12B, Gemma 3 12BHugging Face API GGUF file sizes (bartowski/*-GGUF) + model config.json verified · read 2026-10-23
Piper (TTS)0 GBMantella FO4 docs (Piper ~0.1 GB RAM); SkyrimNet README (CPU-only) verified · read 2026-10-23
xVASynth (TTS)1 GBCHIM wiki Auto-TTS-Voices (≤1 GB) verified · read 2026-10-23
MeloTTS (TTS)1 GBCHIM wiki (≤1 GB) verified · read 2026-10-23
Pocket TTS (Kyutai) (TTS)0 GBSkyrimNet README; Cyberpunk mod 35436 (Pocket runs on CPU) verified · read 2026-10-23
Kokoro-82M (TTS)2 GBhangry-labs KokoroTTS VRAM benchmark (peak reserved 2.05 GB, 03.10.2026) verified · read 2026-10-23
XTTS v2 / CHIM XTTS (TTS)4 GBCHIM wiki (4 GB); Mantella FO4 docs (XTTS+Whisper 3–4 GB) verified · read 2026-10-23
Chatterbox (500M) (TTS)6 GBresemble-ai/chatterbox issue #44 (6–7 GB community reports); macrostack.net (5–6 GB) secondary source · read 2026-10-23
OmniVoice (Cyberpunk mod) (TTS)2 GBnexusmods.com/cyberpunk2077/mods/35436 verified · read 2026-10-23
Cloud TTS (ElevenLabs/Inworld/Voxtral) (TTS)0 GBSkyrimNet README, CHIM wiki verified · read 2026-10-23
Whisper tiny…large (STT)1 / 1 / 2 / 5 / 10 / turbo 6 GBgithub.com/openai/whisper README (PyTorch). whisper.cpp / faster-whisper usually need much less verified · read 2026-10-23
Mantellamod docsgithub.com/art-from-the-machine/Mantella README + docs installation.html; nexusmods.com/skyrimspecialedition/mods/98631 verified · read 2026-10-23
CHIMmod docsdwemerdynamics.hostwiki.io/en/Offline-LLMs, /Auto-TTS-Voices; dwemerdynamics.com/chim/installation.html; Nexus 126330 verified · read 2026-10-23
SkyrimNetmod docsgithub.com/MinLL/SkyrimNet-GamePlugin README + releases; synergyvr.org/mgo/skyrimnet/setup verified · read 2026-10-23
AI NPC LLM Companionsmod docsnexusmods.com/cyberpunk2077/mods/35436 verified · read 2026-10-23
OpenRouter limitsfree ~50 req/day; 1,000/day after $10Steam discussion AI Influence 691997369114401230 (free-tier limits); dwemerdynamics Offline-LLMs; synergyvr.org secondary source · read 2026-10-23
GPU VRAM sizes (34)6–32 GBmanufacturer specs (commonly known values), not individually re-verified; check against TechPowerUp GPU DB secondary source · read 2026-10-23