NVIDIA RTX 3090 vs AMD RX 6600 XT for local LLMs
165 reports on the NVIDIA RTX 3090 and 2 on the AMD RX 6600 XT
Which is faster for local LLMs?
Nobody has reported the same model at the same quant on both cards yet, so there's no measured head-to-head. Memory bandwidth, which caps how fast a card can write, is 3.7x higher on the NVIDIA RTX 3090 (936 GB/s on the NVIDIA RTX 3090, 256 on the AMD RX 6600 XT). The estimates below compare them on the models people run most.
NVIDIA RTX 3090
- Memory
- 24GB
- Memory bandwidth
- 936 GB/s
- FP16 compute
- 142 TFLOPS
- Reports
- 165
AMD RX 6600 XT
- Memory
- 8GB
- Memory bandwidth
- 256 GB/s
- FP16 compute
- 21.2 TFLOPS
- Reports
- 2
Estimated by the calculator
The quant the calculator recommends for each card and its estimated speed at a 32,768-token context with 32 GB of system RAM, from memory bandwidth and the model's shape.
| Model | NVIDIA RTX 3090 | AMD RX 6600 XT |
|---|---|---|
| Qwen3.8 27B | 33.9 t/sQ4_K_M | 1.6 t/sQ6_K, layers on CPU |
| Qwen3.8 125B · 6B active | 19.4 t/sQ2_K, experts in RAM | doesn't fit at these settings |
| DeepSeek V4 Flash 284B · 13B active | doesn't fit at these settings | doesn't fit at these settings |
| Qwen3.6 35B · 3B active | 120.1 t/sQ4_K_S | 14.3 t/sQ5_K_M, experts in RAM |
| Qwen3.6 27B | 33.9 t/sQ4_K_M | 1.6 t/sQ6_K, layers on CPU |
| Gemma 4 26B · 4B active | 76.4 t/sQ5_K_S | 9.1 t/sQ6_K, experts in RAM |
Change the context, RAM or model in the calculator: NVIDIA RTX 3090 · AMD RX 6600 XT
Every report on each card, with its source: NVIDIA RTX 3090 · AMD RX 6600 XT