W530 - CPU drops when I plug in a monitor on battery

Hi

I'm running the "High Performance" power plan, but for some reason my CPU speed drops as soon as I plug in an external monitor (using the 15-pin port).

This only happens while I am on battery.

If I unplug the external monitor then my CPU goes back up to full speed (3.7Ghz).

 

CPU should automatically adjust on battery - does it maximize at full speed if you run anything heave or does it stay on the lowered speed?

Should check the High Performance plan to see the min and max CPU speeds. If the min and max are both 100% and yet the CPU lowers, that's definitely an issue - otherwise, the CPU may just be adjusting itself when you plug into the monitor but is ready to ramp up again instantly.

 

Hi and thanks for the reply.

I am running on the "High Performance" power plan so the CPU min/max is set to 100% (on battery) and the cooling profile is set to active.

The behaviour is weird though. If I just turn on the laptop and start using it then the CPU clock speed is showing at 3.7Ghz (which is the stated maximum speed for an i7-3820QM). If I then plug-in an external monitor then the speed drops down to 1.2 Ghz .. and stays there (after several hours). I have tried about 5 different power plans now and the behaviour doesn't change.

It means that things like flash games, or my virtual machines which I use for development, are running really slowly (despite having full battery and everything being set to "maximum performance"). If I un-plug the external monitor then everything comes back at full speed again.