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I run windows 7 on a Dell latitude laptop.
I use on my laptop a charger from another, older laptop - both Dell.

I got this message:

enter image description here

The battery charges very slow - I understand this, not enough power. My issue is that my computer slows down. All my applications run slowly.

My question is: Is there is anything I can set to improve my computer performance in this case?

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migrated from Nov 24 '12 at 16:56

This question came from our site for professional and enthusiast programmers.

Is your computer equally slow when no power adapter is plugged in? Or is it much slower then on battery power? The reason I asked is because windows has difference performance plans. Most laptops switch to performance mode when connected to a power plug and connect to battery saving mode (and lower performance) when on battery. In your case it might just have switched to this. –  Hennes Nov 24 '12 at 17:45
My computer runs normally on battery, the same speed when it's original charger is plugged in. The only issue is with not original charger, this is the only case when my computer runs slow. –  Zelter Ady Nov 24 '12 at 18:00

2 Answers 2

Stop using the underrated AC adapter. Do as it suggests and get one that provides the 90W required by the notebook.

Until then it won't be able to provide the right power to both run and charge the notebook, so it will slow down in an attempt to keep things running while there is a lack of power. Forcing it to run full speed (if even possible) while providing a lack of power may harm either the AC adapter, or the notebook itself.

See these SU questions and answers for more information:

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Worst of all, it will heat up the charger and can possibly cause a fire or premature failure, possibly including shorting out your laptop's power supply or worse. Compared to a $10 replacement off ebay, it's hardly worth the risk. –  SilverbackNet Feb 28 '13 at 7:35

Following these instructions can potentially lead to hardware damage or even fire. You're doing it at your own responsibility.

If you can't help it and need to use this specific underpowered power adapter but don't want to pretty much end up with a useless brick due to a severely throttled CPU, I just figured out the way to make it go to the full speed.

Pretty much what you need to do is reboot into the BIOS and in Performance settings disable SpeedStep and C states (I'm not sure which one did it, maybe SpeedStep alone is enough, maybe both).

After that, my CPU stopped locking to 800MHz and performance is as good as ever. Funny enough, the battery is actually charging and not depleting slowly, as I was afraid it might.

As for the concern that the power adapter will overheat and potentially cause fire because it'll try to overexert itself, I don't see it as an issue here myself. It's warm, but not warmer than usual, and not remotely hot.

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I believe this answer should start with a disclaimer, I have added it. If you don't like it you can rollback my edit in edit history or edit your post. –  gronostaj Jan 6 at 22:58
I got no problem with that. –  Artem Russakovskii Jan 7 at 23:42

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