Laptop underperforming wheb plugged in

[Kevocalypse]

For some reason when ever I play BF3 when plugged in my cpu speed drops to 1.8 from 2.8. This causes the game to run at 25-30 fps in multiplayer which isn't very smooth. When I unplug however my cpu goes back to 2.8 and my fps goes up to 45-50 and sometimes even 60 in multiplayer. However it randomly drops to 9-12 fps every couple of seconds and skyrockets back up which makes it unplayable. This doesn't really make much sense. My temps aren't high and I'm running on high performance mode for both plugged and unplugged.
CPU: A8-5557m
GPU: 8750m w/ 2gb of vram
8 gb ram
Acer Aspire v5 552g-8632

 

[Matt1970]

Go into your power settings. Under choosing when to turn off the display there is the option for advanced power options. Under processor power management make sure maximum processor state for plugged in is 100%. If that is windows 8 the menus may be a little different.

 

[earthling30]

Some laptops while run at a slower speed when the wrong power pack is used or even when the original power pack is going bad, seen it on multiple times. In some cases it'll tell you just that at P.O.S.T. when the laptop is turned on with the suspect power pack plugged in the laptop, that is if the message hasn't been disabled in the BIOS.

 

[corkyg]

Having the correct A/C adapter is assumed, i.e., assume you are using the one that came with the l;aptop. So, try this. Remove the battery physically and then run on only A/C power, and see if the same problem exists.

 

[marcplante]

Check advanced power management settings for throttled cpu gpu to save power