direct comparison under identical conditions
RTX 3090 Chapter 2 vs RTX 5090 Chapter 1 Local LLM Comparison
If putting a large model is your priority, two 3090s are right, and if single GPU speed and simple configuration are your priorities, one 5090 is right for you.
core difference
| Measure | 2× RTX 3090 48GB (NVLink) | RTX 5090 32GB |
|---|---|---|
| Available fast memory | 45GB | 30.5GB |
| Memory bandwidth | 1872GB/s | 1792GB/s |
| Sustained LLM power | about 780W | about 620W |
| Korean price range (KRW) | 330–440 × KRW 10,000 | 620–780 × KRW 10,000 |
Which device suits the task?
| purpose | superior equipment | reason |
|---|---|---|
| Chat / coding | 2× RTX 3090 48GB (NVLink) | In token generation with the same model, the side with higher memory bandwidth has an advantage. |
| Documents / RAG | 2× RTX 3090 48GB (NVLink) | The side with larger available memory provides more headroom for longer contexts and KV cache. |
| Image / video | RTX 5090 32GB | Let's look at generation tool compatibility and available GPU memory together. |
| Setup | 2× RTX 3090 48GB (NVLink) | Compare finished product status and initial driver·system configuration burden. |
| Power / space | RTX 5090 32GB | Prioritize the side with lower sustained power load. |
Local pricing
2× RTX 3090 48GB (NVLink) consists of 2 GPUs, while RTX 5090 32GB is a single GPU price. When comparing single GPU prices, the base cost of the GPU itself must be added.