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turing-multi-gpu-llm-server/benchmarks/PCIE_LAYOUT_BASELINE.md
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PCIe Layout & Performance Baseline (Pre-Hardware Change)

Date: 2026-09-02
Host: HPE ProLiant DL380p Gen8 (Dual Intel Xeon E5-2620 v2 @ 2.10GHz)
Driver: NVIDIA 610.43.03 (CUDA 13.3)
Server Binary: xrip/llama.cpp-avx1-numa-sm75 with native NCCL Ring AllReduce
Model: Qwen3.8-27B-Uncensored-HauhauCS-Aggressive-Q4_K_P.gguf (MTP Speculative n_max=2)


1. Baseline Hardware & PCIe Bus Layout

GPU ID Model VRAM Bus ID Current Link Max Link Capability Current Power Limit
GPU 0 NVIDIA GeForce RTX 2060 12GB 12 GB 0000:04:00.0 PCIe Gen 1 x16 PCIe Gen 3 x16 184W (Max 215W)
GPU 1 NVIDIA CMP 50HX 10GB 10 GB 0000:07:00.0 PCIe Gen 2 x4 PCIe Gen 2 x16 150W (Max 225W)
GPU 2 NVIDIA CMP 50HX 10GB 10 GB 0000:21:00.0 PCIe Gen 2 x4 PCIe Gen 2 x16 150W (Max 225W)
  • Total VRAM: 32 GB GDDR6
  • Idle Cluster Power: ~33W (11W / 9W / 13W)
  • Model Cold-Start Load Time: 15.7 seconds

2. Baseline Inference Benchmarks

Workload Prompt Tokens Completion Tokens Prefill Speed Decode Speed Draft Acceptance Rate Wall Clock Time
Short Prompt (Code Generation) 69 tokens 256 tokens 14.8 tok/s (1825 ms) 28.4 tok/s (8988 ms) 61.4% (140/228) 11.67 s
Medium Context (~1,000 tokens) 1,074 tokens 256 tokens 276.6 tok/s (3731 ms) 37.1 tok/s (6877 ms) 63.4% (142/224) 11.39 s
Long Context (~4,800 tokens) 4,862 tokens 256 tokens 380.4 tok/s (12672 ms) 38.8 tok/s (6571 ms) 67.0% (146/218) 20.23 s

3. What to Watch For After PCIe Reseating / Slot Change

  1. RTX 2060 Link Generation:
    • Current: Gen 1 x16 (2.5 GT/s)
    • Target / Potential: Gen 3 x16 (8.0 GT/s) or Gen 3 x8 -> 3.2x to 6.4x bandwidth increase to GPU 0.
  2. CMP 50HX Link Width & Generation:
    • Current: Gen 2 x4 (5.0 GT/s x4)
    • Target / Potential: Gen 2 x8 or Gen 2 x16 (if plugged into x16 electrical slots or riser 2).
  3. NCCL Ring AllReduce Latency:
    • Upgrading GPU 0 to Gen 3 and opening higher link widths on GPUs 1 & 2 will directly reduce AllReduce synchronization time between transformer layers, boosting both prefill tok/s and decode tok/s.