You need to talk to HP about how to change this in their bios. However, it will not help you. What is important is that your graphics will take up to 50% of your SYSTEM memory for your games.
There was a registry hack that used to allow this to be changed, but this capability appears to have been eliminated with the DCH rearchitecture.
I hope that you people are also screaming at the games developers who are responsible for the bugs and simply awful designs that created this need.