Let's not exaggerate: it's "only" 170W. Comparing the old 170W http://shop.lenovo.com/us/en/itemdet...FC10#techspecs PSU to the http://shop.lenovo.com/us/en/itemdet...2DF3#techspecs new one, it's significantly lighter although of course a 1.32lbs PSU Is hardly lightweight.

However, this is silly business. You could create a cable that made the W530 think it got a 170W adapter https://forums.lenovo.com/t5/ThinkPa...0W/td-p/841161 when, in fact, you had a 90W. What's the worst can happen? You overdraw your adapter. Any quality adapter (and Lenovo is good) will just shut down. As far as the laptop is concerned that's not different from unplugging the adapter off the wall and it's quite prepared to deal with that. I would not be surprised, at all, if someone made the P90 run with a 90W adapter. Not sure about Windows but Linux has governors where you can set to be powersave and I presume then the laptop would definitely eat less than that 90W. It must be because the http://shop.lenovo.com/ae/en/itemdet...E7BA925BCE90CA battery happens to be 90Wh, the battery life at 90W would literally be one hour but Lenovo claims 6 hours which is of course never realistic but let's call it three hours, that means the laptop eats 30W. Let's use another 30W for charging the battery -- if Lenovo had any brains it'd let you use the 65W and let you choose between performance vs charger weight.