How to reduce DWM.EXE due to memory over committed

Hyper-V OS: WS2012 Std

Guest OS: WS2012 Std

Physical memory: 12 GB

Virtual Memory assign: 8GB (Dynamic Memory)

Recently I installed WS2012 Std edition into my Hyper-V. I'm planning to install SCOM 2012 Sp1 in my VM. I encounter an issue with memory over commit. On resource monitor I found "DWM.exe" cummit up to 19,844KB. I wonder why every time I increase the memory the available memory still got not enough.

Below is the details memory usage:

In Use: 7.8GB

Available: 181MB

Committed: 7.8/9.2 GB

Cache: 175MB

Paged pool: 72.3MB

Non-paged pool: 23.4MB

Appropriated it to any expert will answer my question.

Thanks.