High CPU usage with new power adaptor.

Has anyone come across this problem with the Dell Vostro 1700 before.

The Dell power adaptor failed two days ago (it was 2 years old so I guess that’s the usual lifetime for one of these things) and I have bought a generic adaptor from Micodirect in the UK.

This new adaptor runs at either 19 or 20v and the Dell requires 19.5V. When I plug it into the laptop I get a message saying something along the lines of “Dell AC adaptor not identified” and the laptop then runs off mains power only, the battery does not charge – the battery charge has remained at 65% for the last few days or so. I set the power adaptor to 20v.

However the laptop now runs very very slowly, both cores are running at 70-90% all the time, but when I unplug the power lead the CPU usage drops to normal. This is weird!? What’s happening and why should a different power supply slow the laptop down so much?

I’ve got a new Dell branded adaptor on order, should be here in a couple of days but if anyone can help me out in the meantime I’d appreciate it.

 

Dell notebooks don't like generic PSUs - they expect a signal with the PSU power rating. When there's no affirmative info then the computer does various power reducing measures, such as throttling the CPU.

There is a work-around: Install RMClock (see the undervolting guide) then configure the Performance on Demand power profile to use throttling and select the 100% value only. Then set RMClock to use that profile.

Alternatively, buy a genuine Dell PSU. This 90W PSU is probably OK (check the power rating on the label on the bottom of your notebook).

John