Dual GPUs vs Bigger Card for 31B LLMs
A LocalLLaMA user asks whether it is better to run 27B to 31B models on a single larger-VRAM GPU or on two 16 GB cards, given the overhead of multi-GPU inference. The post compares a single 32 GB class card against dual 7800 XT-style setups and asks whether the extra VRAM is worth the added PCIe and software complexity in llama.cpp, with vLLM mentioned as a possible alternative for dual-GPU runs.
Hot take: for interactive local inference, more VRAM on one card is usually cleaner and more predictable than splitting across two consumer GPUs unless the model simply will not fit.
- –`llama.cpp` supports multi-GPU splitting, but that does not remove synchronization overhead; it mainly helps fit larger models.
- –`vLLM` has first-class tensor-parallel inference, so it is the more natural choice if the goal is multi-GPU serving rather than single-user tinkering.
- –A 32 GB card is a meaningful step up because it reduces or eliminates the need to shard weights and leaves more room for KV cache and longer contexts.
- –Dual 16 GB cards can be a practical capacity play, but they usually trade simplicity and latency consistency for extra tuning and bus overhead.
- –For 27B to 31B models, the real decision is often “fit comfortably on one device” versus “fit at all across devices,” not “scale linearly with more GPUs.”
DISCOVERED
45d ago
2026-04-26
PUBLISHED
45d ago
2026-04-26
RELEVANCE
AUTHOR
rebelSun25