Inconsistent memory consumption?

This might not be an issue but a misunderstanding.
I run FastFlowLM on a Ryzen AI 7 360 PRO NPU with 64GB VRAM.
The purpose is to run visual tasks on NPU and I am selecting a model for perf/RAM among the QWen3.5 family. I try 2B, 4B, and 9B models with 4k/8k context window size to concisely read short text from a 1080x720pix PNG image.

What is confusing: On model load, the consumed RAM is slightly different - OK, but when I run inference on the models they all end up with the same 27GB consumed RAM, which is very confusing. Also the context window size does not have an effect. I expected to see less RAM consumed by smaller models.

Here are RAM consumption details:

• QWen3.5-2B
  • On load: 4.2GB
  • On inference: 27GB
• QWen3.5-4B
  • On load: 5.5GB
  • On inference: 27GB
• QWen3.5-9B
  • On load: 9.0GB
  • On inference: 27GB

Am I supposed to expect the same RAM consumption, no matter the LLM size: 2B/4B/9B?

Start by reproducing the reported RAM measurements for the QWen3.5 2B, 4B, and 9B models with 4k and 8k contexts, recording usage at load and inference. Trace the inference and memory-management paths involved; done means determining whether the shared 27GB usage is expected or isolating a reproducible defect.