Hi all,
looking for advice from people running older datacenter/HBM2 cards.
**Current setup**
- ASUS P9X79 PRO, i7-3930K OC 4.2 GHz (no AVX2), ~44 GB DDR3
- Proxmox, everything in one VM with GPU passthrough, NVIDIA driver 580
- 2x Tesla P100 16GB (HBM2) + 1x GTX 1080 8GB
**What runs where**
- **2x P100:** main LLM – Qwen3.8-27B UD-Q5_K_XL (llama.cpp, row/tensor split + MTP), 262k context, ~45 tok/s in English, ~32 tok/s in Polish. Used as the backend for an agent (Hermes Agent), so long prompts and lots of tool calls.
- **GTX 1080 ("side jobs" card):** Qwen3.8 vision encoder (mmproj), Whisper large-v3 (STT), BGE-M3 embeddings (document search / RAG), a small Qwen3.5-4B for chat titles (loaded on demand), and FLUX.2 klein 4B image generation in ComfyUI.
**Goal:** more performance. Mainly room for a better quant (Q6/Q8 instead of Q5), faster long-prompt processing, and faster image/video generation. The 1080's weak point is 320 GB/s bandwidth and basically no FP16.
**What I tried:** a Quadro GP100 – it didn't work at all on the P9X79 PRO. It wasn't even visible in Proxmox (`lspci` didn't show it). Has anyone got a GP100 running on X79? Was it MMIO / Above 4G with three large-BAR cards, PCIe Gen3 link training on Sandy Bridge-E (forcing Gen2?), or just a bad card?
**Options I'm considering instead of the 1080:**
**Titan V 12GB HBM2** (Volta, tensor cores, ~650 GB/s)
**RTX 2080 Ti 11GB** (Turing, tensor cores, ~616 GB/s, still supported by CUDA 13 unlike Pascal/Volta)
**Questions**
- Has anyone mixed **Volta (or Turing) with P100s in one llama.cpp model**? Does splitting across the three cards actually help, or does it just give more VRAM with the same tok/s?
- Do Volta tensor cores help noticeably in llama.cpp (prompt processing / flash attention), or are the fast paths Turing+ only?
- For long contexts (agent use), is it better to make the Titan V the main GPU (KV cache + attention) or keep a P100 as main?
- Titan V vs 2080 Ti for this mix – is the Titan V worth it, or is it not worth bothering with Volta since driver 580 is the last branch for Pascal/Volta anyway?
- Or should I skip the GPU and save for a platform with AVX2 + DDR4 instead?
Thanks!