AMD RX 7800 XT 16GB vs AMD RX 7900 XTX for local LLMs
8 reports on the AMD RX 7800 XT 16GB and 47 on the AMD RX 7900 XTX
Which is faster for local LLMs?
On Qwen3.8 27B at 4-bit, the AMD RX 7800 XT 16GB has 35.0 generation tokens/s (2 runs); the AMD RX 7900 XTX has 42.5 generation tokens/s (6 runs); prompt processing 640.0 tokens/s (4 runs). Those are community reports whose engines and settings differ, so the gap is a rough sign, not a controlled measure of the two cards. Memory bandwidth, which caps how fast a card can write, is 1.5x higher on the AMD RX 7900 XTX (624 GB/s on the AMD RX 7800 XT 16GB, 960 on the AMD RX 7900 XTX).
- Memory
- 16GB
- Memory bandwidth
- 624 GB/s
- FP16 compute
- 75 TFLOPS
- Reports
- 8
- Memory
- 24GB
- Memory bandwidth
- 960 GB/s
- FP16 compute
- 123 TFLOPS
- Reports
- 47
Measured on both
Generation and prompt processing speeds from plain runs (one device, one request, no speculative decoding, the whole model in the device's memory) of the same model size at the same bit class. Each side shows the engines and reported context behind its median. Context can mean a configured window or prompt depth, so these are community comparisons with differing settings. How to read these
| Model | AMD RX 7800 XT 16GB | AMD RX 7900 XTX |
|---|---|---|
| Qwen3.8 27B4-bit | 35.02 runsllama.cpp, 1 not stated100K to 120K context | 42.56 runsPP 640.0 (4 runs)llama.cpp, Ollama, 2 not stated64K to 220K context, 3 not stated |
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. Where a model was also measured above, the measurement wins.
| Model | AMD RX 7800 XT 16GB | AMD RX 7900 XTX |
|---|---|---|
| Qwen3.8 27B | 40.7 t/sQ2_K | 34.8 t/sQ4_K_M |
| Qwen3.8 125B · 6B active | doesn't fit at these settings | 19.5 t/sQ2_K, experts in RAM |
| Qwen3.6 35B · 3B active | 134.6 t/sQ2_K | 123.2 t/sQ4_K_S |
| DeepSeek V4 Flash 284B · 13B active | doesn't fit at these settings | doesn't fit at these settings |
| Qwen3.6 27B | 40.7 t/sQ2_K | 34.8 t/sQ4_K_M |
| Gemma 4 26B · 4B active | 90.7 t/sQ3_K_S | 78.4 t/sQ5_K_S |
| DeepSeek V4.1 Flash 552B · 16B active | doesn't fit at these settings | doesn't fit at these settings |
Change the context, RAM or model in the calculator: AMD RX 7800 XT 16GB · AMD RX 7900 XTX
Every report on each card, with its source: AMD RX 7800 XT 16GB · AMD RX 7900 XTX