170W adapter for gaming laptop in Japan

Hi guys. I live in Tokyo and I recently ordered a Lenovo IdeaPad Y510p along with a 2nd graphics card for a better gaming experience. The laptop comes with an optional "Ultrabay" slot where the 2nd graphics card can be put in to make use of an SLI.

My problem is that the laptop needs a 170W adapter to power the SLI setup. My adapter hasn't arrived yet but I heard that since the voltage and frequency of electricity in Tokyo is weaker than that of the United States (only 100V and 50Hz in Tokyo) I won't be able to power my SLI setup in my laptop without some sort of expensive voltage converter.

Am I fine without a voltage converter? Also, plugs and outlets here are ungrounded so would using a plug adapter have any effect on my adapter/laptop? Any help is much appreciated.

Most notebook power adapter or AC/DC adapter are universal power , 100-240V 50-60Hz .
so there should be no problem in term of power supply.
As long as your power adapter output/rated 170W then its good.

Has your adapter arrived yet? As mentioned the input doesn't really matter (virtually all laptop adapters are universal voltage). Only the rated output matters which is listed on the adapter itself.

The adapter hasn't arrived yet but I know it's output. The output is 20V 8.5A. Will this work?

Watts = Volts * Amps so 20V * 8.5A = 170W

So yes, it looks like the power adapter that comes with the laptop is properly rated for it (go figure).