So the gaming mode power plan should only be used when the laptop is working off of the AC adapter. I just searched a couple of forums and I just read that, a laptop can work without the battery installed, but you just need to have it plugged in the wall or any electrical outlet. It's funny, if you think about it in a way, EMU's are powered by the 3rd rail or catenary. Once there is no more, catenary or 3rd rail, they are unable to continue their journey.