AM AMD Consumer Discrete GPU

AMD Radeon RX 6800 XT

Runs downloadable LLMs up to ~19.5B at Q4, ~72-88 tok/s on an 8B model.

AMD Radeon RX 6800 XT
16GB
VRAM
512
GB/s bandwidth
19.5B
Max model (Q4)
$649
MSRP

What you can run

At 8k context, FP16 KV. Full-speed tok/s holds up to "max ctx"; beyond it the context spills to system RAM (CPU/PCIe offload) and drops to the degraded figure.

Model sizeFP16Q8Q4
3B 53.8-65.7 t/s
≤110k ctx · then ~4.2-5.1 (slow)
107.5-131.4 t/s
≤156k ctx · then ~8.4-10.3 (slow)
192-234.7 t/s
≤176k ctx · then ~15-18.3 (slow)
7-8B won't run 40.3-49.3 t/s
≤40k ctx · then ~3.2-3.9 (slow)
72-88 t/s
≤67k ctx · then ~5.6-6.9 (slow)
13B won't run 24.8-30.3 t/s
≤1k ctx · then ~1.9-2.4 (slow)
44.3-54.2 t/s
≤36k ctx · then ~3.5-4.2 (slow)
32B won't run won't run won't run
70B won't run won't run won't run
120B won't run won't run won't run
400B won't run won't run won't run

Estimate: tok/s ≈ bandwidth ÷ (params × bytes/param) × efficiency (AMD). Cyan = fits ~14.7 GB usable. Beyond "ctx", KV spills to system RAM (CPU/PCIe offload) (rough degraded speed shown).

What else you need for a full build

Minimum supporting components for a desktop built around the AMD Radeon RX 6800 XT. Guidance — exact needs depend on your case, other parts and how much you offload to system RAM.

Power supply
≥ 750W · 80+ Gold
Headroom over the 300W card plus the rest of the build.
System RAM
≥ 16 GB · 32 GB recommended
At least the 16 GB of VRAM; 2× lets you CPU-offload models larger than VRAM.
Motherboard
1× free PCIe x16 slot (4.0/5.0)
A full-length x16 electrical slot; PCIe 4.0 is ample, 5.0 future-proofs.
CPU
Any modern multi-core
The GPU runs inference; more cores and memory channels only matter when offloading to RAM.
Storage
≥ 1 TB NVMe SSD
Weights are large — a 70B model at Q4 is ~40 GB; budget for a few.

Run popular models on the AMD Radeon RX 6800 XT

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About the AMD Radeon RX 6800 XT

AMD Radeon RX 6800 XT is a discrete GPU from AMD on RDNA 2, 2020. For local genAI the numbers that matter are its 16 GB (how big a model + context fits) and 512 GB/s bandwidth (generation speed). Plan for a ~750W power supply.

Frequently asked questions

What size LLM can the AMD Radeon RX 6800 XT run?

With ~14.7 GB usable it runs up to ~19.5B at Q4 (~6B at FP16) at 8k context. Bigger spills into system RAM (CPU/PCIe offload) and slows sharply.

How many tokens/sec does the AMD Radeon RX 6800 XT generate?

Generation is bandwidth-bound. At 512 GB/s an 8B model at Q4 runs ~72-88 tok/s (estimate).

Why does long context slow it down?

The KV cache for the context must also fit fast memory; once weights+KV exceed 14.7 GB it spills to system RAM (CPU/PCIe offload) and throughput collapses. Each row shows the max usable context.

What else do I need to run the AMD Radeon RX 6800 XT?

Besides the card: a ≥750W 80+ Gold power supply, at least 16GB of system RAM (2× the 16GB VRAM is ideal for CPU offload), a free PCIe x16 slot, any modern multi-core CPU, and a ≥1TB NVMe SSD for model weights.