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I have an old laptop that I need to get a new power supply for, and it seems the only one I can find with the proper connector is 90W, rather than the 65W the original had.

Would it be safe to use the higher wattage? (The laptop is a Dell Inspiron 8600)

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As a rule of thumb, it generally should be safe, but I can't guarantee that for this particular machine so I'm not making this an answer. – Shinrai Nov 16 '10 at 15:53
up vote 4 down vote accepted

Presuming connectors, voltage etc are the same the wattage increase won't be a problem at all.

I've heard a concern that a high-wattage power supply can somehow "force" the power onto the computer, causing overheating and burnout. Nothing could be further from the truth. A power supply supplies power in response to need; it doesn't push power anywhere. If your computer only needs 100 watts, then a 500 watt power supply will only supply 100 watts. Why have a 500 watt power supply? For "peak" usage (sometimes hardware will require sudden "bursts" of power, such as at start up or under high load) and for future expansion.

It's better to have too much power than too little

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The external power-supply "brick" can be a higher wattage but the voltage must match within a few percent. The laptop power connector polarity must be correct too. It should ideally be a properly regulated switched-mode power-supply designed either for that model or similar.

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