Benchmark: Dual R9700 GPUs see 18-32% gain switching to PCIe Gen5 x8
Ramzeus · reddit · 2026-08-25
After upgrading the motherboard (MSI PRO-X670-P to Asus ProArt X870E), the author benchmarked dual AMD R9700 GPUs in vLLM. The new configuration moved both cards from Gen4 x16/x4 to Gen5 x8/x8 (both directly connected to the CPU).
Results:
- At Concurrency 1: PP tok/s +17.9%, TTFT -34.5%.
- At Concurrency 4: PP tok/s +27.6%, TG tok/s +32.3%, TTFT -35.4%.
Conclusion: For AMD dual-GPU AI rigs, upgrading to a matched Gen5 PCIe configuration yields significant performance gains. Benchmarks were run using Qwen 3.8 27B fp8.
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