A few notes:
1.
Quote from: that escalated quickly on August 28, 2026, 11:32:08or the cheaper X870E Taichi Lite
QuoteBeware Asrock boards are known to fry the Ryzen 9800X3D. r/pcmasterrace has quite a few stories.
..
So while I had the same experience with ASR that is often reported here, I'm not sure whether it's really an ASR issue or a general one.
2. Why dual GPU? Because not only for pipeline parallelism, but also tensor parallelism (note that tp is supposedly finicky and requires ideally the same GPUs and the PCIe lanes go to the CPU directly)
3.
Quote from: that escalated quickly on August 28, 2026, 11:32:08PCIe 5.0 x8
Note, the GPU itself also has to support PCIe 5.0, otherwise the connection will downgrade to whatever the GPU's generation is, e.g PCIe 4.0 x8.
4. PCIe 5.0 x16/x8x8 is only supported by Ryzen 7000 and 9000, Ryzen 8000 only supports PCIE 4.0 x16/x8x8.
5. PCIe 5.0 x8 = PCIe 5.0 x16, so the performance loss is only a few percent (search engine for: "PCIe scaling", TPU has an article)
Other relevancies: Club 3090 / 4090 / 5090, P2P driver patch, NCCL.
"I've done the homework, here are the latest generation AM5 motherboards with x8/x8 Gen 5 that can fit 2 GPUs with 3.5 slots thick GPUs ranked by me": reddit.com/r/LocalLLaMA/comments/1nx1nkv/comment/nhne8vv/
Use this sub to search: reddit.com/r/LocalLLaMA/search/?q=SEARCH TEXT
(e.g. pipeline parallelism vs tensor parallelism)