Wednesday, June 8, 2011

Laptop Runs Faster On Battery

Here's a Dell Latitude e6400 with SpeedStep turned on running with the charger plugged in.

A Core 2 Duo running at 800Mhz?! Yup, the multiplier has been set to 6 and the frequency is halved at 133.

Ok, let's unplug the power and run off battery.

Oh, hey, 2.5GHz. That's more like it.

Unfortunately, this means I get full speed for about two hours then have to put up with 800MHz on battery.

But what happens if we disable SpeedStep? Well, then it sets it to the lowest clock multiplier of 6, but the regular frequency of 266, and I get about 1.6GHz all the time, on charger and battery.

What I'm guessing is that the 65W charger that the laptop came with doesn't provide enough power to run the laptop at full speed. A 90W charger may solve the issue, but I don't have one to test with.

For now, I'll probably just compromise, turn off SpeedStep and run at 1.6GHz. 

p.s. Turning off SpeedStep has to be done in the BIOS and requires a reboot. Ugh.