club-3090/docs/HARDWARE.md

Hardware notes

What this stack assumes about your hardware. True regardless of which model or engine you're running.

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Required

• NVIDIA RTX 3090 (24 GB, Ampere SM 8.6) — 1 or 2 cards.
• PCIe Gen 4 slot — Gen 3 works but allreduce on dual-card is slower (mild impact on multi-tenant; minimal impact on single-stream).
• NVIDIA driver 580.x or newer — for CUDA 13 runtime in vLLM nightly. nvidia-smi to check. Older drivers won't load CUDA 13 kernels.
• Linux (Ubuntu 22.04+ tested). vLLM is Linux + CUDA only. llama.cpp works on macOS / Windows but our recipes assume Linux paths.
• Docker + NVIDIA Container Toolkit for vLLM. llama.cpp doesn't need Docker.

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Other Ampere/Ada cards

The recipes are written against 3090 specifically but should work on:

Card	VRAM	Compute capability	Notes
RTX 3090	24 GB	sm_86	Tested. Default target.
RTX 3090 Ti	24 GB	sm_86	Should work; same VRAM, slightly higher TPS expected
2× RTX 3080 modded 20 GB	20 GB / card (40 GB combined)	sm_86	Tested 2026-05-02 by @troymroberts (#25) at 200W/card power limit. dual.yml (TQ k8v4 KV + MTP K=3) boots at full 262K target with gpu-memory-utilization=0.82 (down from shipped 0.95 — see note below). Available KV pool 5.2 GB/card, max concurrency 1.43×. verify-full 10/10 pass; bench 49 TPS wall single-stream, 210 TPS aggregate at n=8. First published SM86 / 40 GB combined data point outside the 3090 family.
RTX 4090	24 GB	sm_89	Should work; ~30% faster decode (newer SMs); same memory characteristics
RTX 5090	32 GB	sm_120	Untested; more VRAM relaxes the prefill cliffs but kernel paths might differ
RTX A5000	24 GB	sm_86	Sander's PROD class for genesis-vllm-patches. Identical SM and VRAM to 3090; should run identically.
RTX A6000	48 GB	sm_86	Should work; double VRAM lets you skip the cliff workarounds (use Sandermage's reference defaults)
H100 SXM	80 GB	sm_90	Different beast; flash-attn 3 paths available; not what these recipes target

Won't work: anything with <20 GB VRAM (3060, 3070, stock 3080, 3080 Ti). The 27B model in INT4 is ~18 GB — KV pool + activations push past 24 GB on smaller cards even with aggressive quantization. Modded 20 GB 3080s do work (see row above) — the mod gives them enough headroom for the 27B + TQ K8V4 KV path on TP=2, with mem-util=0.82 to absorb cudagraph profiling overhead.

Note for sub-24 GB cards

On 20 GB cards (modded 3080) the cudagraph-profiling overhead is a meaningful slice of available VRAM. Drop --gpu-memory-utilization to 0.82 (vs shipped 0.95 for 24 GB). vLLM nightly's gpu_worker.py reports the equivalent effective KV size in the boot log; tune to keep activation headroom for the ~15K tool-prefill peak (verify-full check 8). Credit: @troymroberts.

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NVLink

Not required. We've explicitly designed for PCIe-only consumer setups.

• 3090s have an NVLink connector but a bridge has to be physically installed. Most consumer setups don't have one. (Cost: ~$70-150 for a working 3-slot bridge if you wanted to add one.)
• Our composes set NCCL_P2P_DISABLE=1 and avoid NVLink-dependent allreduce paths.
• If you have NVLink installed and working, single-stream TPS on dual-card will be ~1.6-1.8× single-card (vs ~1.05× without). Concurrent throughput scales similarly. Not a huge deal unless you really care about per-stream speed.

The user explicitly chose to operate without NVLink. Don't suggest adding one.

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Power

Production target: 230W per card (default cap, quiet, cool, stable).

Power lever:

sudo nvidia-smi -pl 230 -i 0    # production default
sudo nvidia-smi -pl 330 -i 0    # ~+10% mean TPS during heavy sessions

Past 330W: diminishing returns (SM clocks saturate near 1.9 GHz on 3090s).

For dual-card: combined power at 230W cap each = ~460W. Most modern 850W+ ATX PSUs handle this comfortably. If you push to 330W per card, you're at ~660W peak under heavy load — verify your PSU has at least 850W single rail.

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VRAM ceilings (the cliffs)

This is model-specific but the shapes apply across hybrid-attention models (Qwen3-Next family, similar architectures):

• Single 3090 (24 GB): Cliff 1 (~25K-token tool prefills, FFN intermediate buffer) closed across all shipped variants since 2026-04-30 PM via Genesis PN8 / PN12 anchor sidecar. Cliff 2 (~50-60K single prompts, DeltaNet GDN forward) still applies. See docs/CLIFFS.md for the full diagnostic.
• Dual 3090 (48 GB combined): TP=2 splits activation memory across cards. Cliffs are not active failure modes.

For visualization of how VRAM splits across single + dual configs, see vram-budget-combined.svg (or per-page: single · dual).

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Disk

• Per model: ~20 GB for weights + Docker layers + scratch.
• Per engine: vLLM Docker image is ~9 GB. llama.cpp binary is ~50 MB.
• For dual-card vLLM: add ~2 GB for the patched vLLM source clone (/opt/ai/vllm-src/).

If you'll run multiple models, plan ~20 GB each.

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Things this stack doesn't support (hardware-wise)

• macOS / Windows native — Linux only (vLLM constraint). WSL2 might work but isn't tested.
• AMD GPUs — vLLM has experimental ROCm support but we haven't validated. llama.cpp works on AMD via HIPBLAS.
• Apple Silicon — llama.cpp via Metal works for the model, but our recipes are Linux-x86-64 path-specific.
• Intel GPUs — llama.cpp via SYCL/oneAPI has support; not tested by us.

If you're on non-NVIDIA hardware, /docs/engines/LLAMA_CPP.md is your starting point.