Side-by-side simulation · recommended settings
RTX 4090 vs RTX 5080: Is the newer card better for local LLMs?
Workloads relying on the 4090's 24GB need a new capacity check on the 5080's 16GB. For smaller models, compare current setups on both; keeping the 4090 is an option when capacity comes first.
Choose devices and a model
Expand comparison settings
Same 117output tokens. Only evidence-qualified acceleration is selected automatically; runtime formats are shown on each device.
Left
ReadyRTX 4090 24GB
Press Start above to generate the same answer on both devices.
Right
ReadyRTX 5080 16GB
Press Start above to generate the same answer on both devices.
With these settings, RTX 4090 24GB finishes the full answer About 1.7× faster.
Compare from input processing to completion of 117 token response.
Which one fits my needs?
Answer completion
RTX 4090 24GB
At the estimate midpoint, it finishes the same answer about 1.7× faster.
Prompt processing
RTX 4090 24GB
The estimated input-processing midpoint is higher at 4,219 tok/s.
Image and video generation
Check the media model
LLM speed does not tell you media-generation performance. Choose the image or video model and resolution separately.
Runtime
Settings for your hardware
Strata 0.1.33 serving branch · IQ3_S · MTP-4 · INT8 KV · SSD PLE / Strata · Blackwell (CC 12.0) · CUDA · MTP · NVMe PLE · single GPU. When runtime paths differ, the speed gap also includes software and model-format differences.
Estimated power draw
RTX 5080 16GB
Estimated LLM power draw is lower at about 352 W. Noise and physical size need a separate check.
Local pricing
RTX 4090 24GB costs about 128 × KRW 10,000 more at the reference-price midpoint, with an estimated answer time about 43% shorter.
Before choosing hardware
| Measure | RTX 4090 24GB | RTX 5080 16GB |
|---|---|---|
| Available fast memory | 22.5GB | 15GB |
| Memory bandwidth | 1008GB/s | 960GB/s |
| Estimated total time | 1.8 s | 3.1 s |
| Estimated sustained LLM load | about 470W | About 352W |
| Korean price range (KRW) | 325–400 × KRW 10,000 | 231–239 × KRW 10,000 |
Estimated ranges for one user. Multi-GPU and multi-device results depend on the runtime and interconnect.
Compare the file and context as a pair
A file can load in 16GB yet leave too little room for long input. Compare using the document length and conversation depth you use on the 4090. Even a promising short-question speed difference can be offset by more offloading in real document work.
Check new runtime benefits on supported models
Engines using Blackwell need matching model formats and kernels. Check the recommendation here and follow the model's guide. If you intend to keep an existing CUDA tool, compare with a file that tool supports too, so the comparison reflects the workflow after replacement.
Name the problem the replacement should solve
If your 4090 is hot or noisy, power limits and cooling adjustments are options to test first. For larger models, expand the comparison to higher-memory configurations. For repeated waiting on the same model, use generation with the recommended setup. Identifying the problem narrows replacement candidates.