In Windows Server 2012, I find myself cool on this dynamic memory on Hyper-V environment, because I ran my virtual labs everyday.
in each virtual labs, you can configure the dynamic memory according your appropriate host server’s capability. Usually, At startup, Windows requires more memory. Also, some application will requires memory. Even though you set to 1GB memory, but when enabling the dynamic memory will help to stabilize your servers. The screenshot below is just the example of dynamic memory. You could also check the performance at your task manager how the memory plays.