Undervolting a Laptop

Delph1 writes "Laptops often comes with two Achilles heels, heat and limited battery time. There are, if not cures, at least remedies to make them less obvious. By lowering the voltage to the processor you can not only drastically lower the heat dissipation, but also increase the battery time significantly. NordicHardware gives a nice walk through on the process and was able to boast 18% lower temperature and a 20% reduced power consumption."

Comments

Computer Performance

[ranton]

How does reducing the Voltage in this way effect performance? If performance drops, then you could have just bought a computer with less processing power that also had lower power needs in the first place.

If there are no performance problems, then why dont all laptop manufacturers already do this?

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Too much misinformation here.

[TheGuano]

Some facts:

Undervolting is NOT underclocking. You run the same clock speed, you just provide the CPU with less juice.

You do NOT need to underclock to undervolt, though if you're trying to hit a super-low voltage, a lower clockspeed will let you do it.

It can be perfectly safe. If you undervolt, and successfully run a Prime95 torture test for 24 hours, you're pretty much set. I'm currently running a 1.8Ghz Dothan Thinkpad at 1.134V (default at 1.8 is 1.340), and 0.700v at 600Mhz (default is 0.980 volts). That's on par or lower than those 1.0Ghz ULV Pentium-Ms!

Rovclock

[wiresquire]

For you Linux-ers who have ATI cards with no PowerPlay (it's disabled in my video BIOS - bastards!!), I'd recommend checking out rovclock.

While it doesn't actually reduce voltage, it can be used to underclock GPU and memory speed. My somewhat unscientific testing has shown no major differences between fglrx and radeon + rovclock with 2D, but I did note a 27% decrease in battery draw for 3D using the fglrx driver.

Of course, you're trading performance for battery life, and why you'd want to eg, play a 3D game on battery I wouldn't really understand

YMMV
ws