Qwen 3.8 27B is excellent, but it defaults to wildly overthinking things
Friday’s big release was Qwen 3.8 27B, an Apache 2 licensed 27B parameter vision-capable LLM from Alibaba’s Qwen research lab. I’ve been looking forward to this one: 27B is an excellent size for running a model on a reasonably specced laptop, and its predecessor Qwen 3.6 27B was impressive.
Qwen’s self-reported benchmarks for this model are eye-opening. They show a boost from both Qwen 3.6 27B and the closed-weight Qwen 3.7-Plus, which was one of Qwen’s strongest models of any size as recently as May this year. It will be interesting to hear what independent benchmarks have to say about the model.
I’ve been running the model on two different machines: my 128GB M5 Max MacBook Pro, and an NVIDIA DGX Spark. On both machines I’m running LM Studio and their 17GB Q4_K_M quantized build. I also tried using llama-server directly on the Spark.
The default of extra high results in spectacular over-thinking
Qwen’s documentation describes the model as defaulting to xhigh for the reasoning effort, and the LM Studio GGUF I’ve been trying preserves that default:
Qwen3.8 comes with official support for reasoning_effort , which can be used to adjust reasoning depth and control cost: xhigh (default): for complex tasks demanding thorough analysis
(default): for complex tasks demanding thorough analysis medium : balancing accuracy and speed
: balancing accuracy and speed low : efficient reasoning optimizing for speed and cost
This is a hilarious default. It’s absolutely not a good way to run the model, especially on consumer hardware. I’ve been finding the results extremely entertaining.
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