Performance comparison: which is faster?
AMD Instinct MI300X (AMD, 2023) and Radeon RX 6900 XT (AMD, 2020) are compared here. Compare scores and VRAM, generative AI usability, and CPUs that pair well with each GPU.
Overall performance: Instinct MI300X is about 254.2% faster
For generative AI, the higher-VRAM Instinct MI300X（192GB） has the advantage. For gaming, prioritize performance score and CPU compatibility; for AI, prioritize VRAM.
Relative performance score (higher is faster). Actual fps varies by resolution, game, and CPU configuration.
| Item | Instinct MI300X | RX 6900 XT |
|---|---|---|
| Performance Score | 85,000 | 24,000 |
| VRAM | 192GB | 16GB |
| Manufacturer | AMD | AMD |
| Series | Instinct | RX 6000 |
| Release Year | 2023 | 2020 |
| Compatible CPU Example | Ryzen 9 9950X3D | Ryzen 9 5900X |
These generative AI models can run on only one GPU because of the VRAM difference (Stable Diffusion, Flux, LLMs, and others).
— None (all models that run on Instinct MI300X also run here)
| If You Want To... | Recommended |
|---|---|
| Prioritize high fps and smooth performance in demanding games | Instinct MI300X |
| Run larger generative AI and LLM models | Instinct MI300X |
| Prioritize value and adequate performance | RX 6900 XT (the lower model is often sufficient) |
Instinct MI300X is about 254.2% higher by score (Instinct MI300X: 85000 points / RX 6900 XT: 24000 points). Actual fps also varies by resolution, game, and CPU, so price is a reasonable deciding factor when the gap is only a few percent.
Instinct MI300X has 192GB of VRAM, while RX 6900 XT has 16GB; Instinct MI300X has more. If image generation or a local LLM is even a possibility, the higher-VRAM option provides more room.
Using our guideline, Ryzen 9 9950X3D pairs well with Instinct MI300X and Ryzen 9 5900X with RX 6900 XT (CPU:GPU ≈ 0.9:1). If the CPU is too weak, replacing the GPU may not raise fps, so check the combination before buying.
