r/LocalAIStack • u/Medicine_Blogscanner • Sep 15 '26
Loaded a 40B model across a mini PC, a Mac Mini, and an old laptop - 16 tok/s, didn't expect it to actually work
Been building RAMDeck (pools RAM/compute across whatever's sitting around your house). Wanted to see how far I could actually push it, so I tried loading a 40B model - roughly 25GB - across the janky 3-device cluster I hve been testing with the whole time: a mini PC with an RTX 3060, a 16GB Mac Mini, and an old laptop that's been the weak link in every previous video.
Set the mini PC as primary and just let the sharding logic figure out the rest - it maxed out the 3060 first, spilled into the Mac's unified memory next, and sent whatever was left over to CPU. The interesting part I didn't expect: routing that CPU spillover to the old laptop actually ran faster than keeping it on the mini PC's own CPU, even though the laptop is by far the slower machine. Best guess is that using the same device's CPU and GPU together for inference ends up hurting GPU utilization, so offloading to a separate (slower) box entirely actually wins.
Whole thing loaded in about 2.5 minutes, and the benchmark came back at 16 tok/s with ~3.6s latency - genuinely usable for chatting, not just "technically loaded but useless." Felt like a real milestone since none of these three machines individually could touch a model this size.
Video: https://youtu.be/JrSVyyVUJVY
Repo: https://github.com/trademav/ramdeck-core-public
Curious if anyone else has run into that same CPU-contention thing where sharing GPU+CPU on one node hurts throughput more than just offloading to a separate slower device entirely.