I recently bought an HP 6730b laptop on auction. I took it out of the container, and turned it on (without attaching the power supply). It's pretty snappy, and seems to be in good nick.
Perfect for my mother, I thought.
I plugged the charger in, and started installing Ubuntu. Good God! It's taking an AGE to even go through the POST, never mind running the OS. Shit! And the auction specified no returns if the OS has been changed! Now what?
Xorg is taking 80% of the CPU, just moving the mouse around. WTF!?
Long story short, it turns out it is the aftermarket power brick that is to blame. Unplug it, run it on battery, works like a dream. Plug it in, and it all goes to shit.
Check the voltage on the brick - all according to spec.
Looks like it is time to get a genuine brick for my mom.
My only thought is that the laptop is spending more time cycling between power saving (C3?) states that it actually does executing the instructions it has been given. Can anyone explain this behaviour better?