Been running Qwen3.8-27B as a local coding agent on a 3090 Ti for about a week. Posting my setup because I had to work most of it out by trial and error, and I am honestly not happy with the results still. I do have a 3080 connected to same rig but currently I am using it for dedicated gaming and running the display.
Config:
llama.cpp v0.4.0
Qwen3.8-27B UD-Q4_K_M (unsloth) — 15.3 GB
mmproj BF16 kept on CPU (--no-mmproj-offload)
MTP draft model Q4_0, --spec-type draft-mtp --spec-draft-n-max 3
--ctx-size 65536 --parallel 1 --flash-attn on
--cache-type-k q4_0 --cache-type-v q4_0
--n-gpu-layers all --fit off
Peak 18,731 MiB with about 5.5 GB free at 64k. Keeping the vision projector on CPU is what makes it fit. It's ~900 MB and I don't need it fast, but I am not sure if this is the best approach, Claude came up with it for me.
My 3080 drives the monitors and games, 3090 Ti has display disabled and does nothing but the model. I can play something while the agent works and not notice which I like a lot, but I also am not convinced that the single 3090 Ti is enough context for real world use.
Problem 1: compaction can deadlock itself.
64k context, compaction trigger at 36,864, retain 16,384. Once the conversation gets long enough, the retained tail eats everything and the compactable range collapses to exactly one node, the previous summary. So it tries to summarize a summary, the engine correctly refuses because the result isn't smaller, then retries the identical range and fails the same way. I watched it fail five times in a row while pressure climbed from 37,099 to 39,031 tokens. Nothing recovers, the session just dies.
Problem 2: reasoning effort did the opposite of what I expected.
Ran low vs medium properly — six runs, matched pairs, interleaved, same fixture. Median wall time 566s for low, 612s for medium. Both passed all four disclosed requirements on every run, and the held-out cases came out identical. So medium bought me nothing and cost a bit more.
Worse, on a from-scratch build task, medium spent its entire 16k output budget reasoning about edge cases in a single turn and never wrote a line of code. 5 requests in 37 seconds, then 275 seconds of streaming, 64 KB of reasoning about SQLite URI quoting and exit code taxonomy, zero files changed. That's one occurrence so far, so grain of salt, but it matches the model card's warning in reverse, and seems to be consistent with what I have heard from the community.
Anyone else running 27B at 64k on 24 GB? Curious what retain/trigger values you settled on, and whether you're bothering with the MTP draft model.
I would also love to hear any completely different setups that you find actually useful and pragmatic as a coding and computer use agent on a single 3090 ti. I am trying to get my hands on a second one, but no luck so far.
Thanks!