I had a client complaining that her laptop was in turn complaining about the power supply was too weak (I think the warning was “your power supply fu is weak!”). I compared the power supply she was using when she took her machine home to the supply on her docking station at her desk. The station supply was 90W while the one she was carrying around was merely 65W.
My opinion is that both should be just fine. This is further supported (beyond my vast experience) by the fact that under most circumstances it was really working more or less fine. The screen would flicker when she was at home (possibly due to weak line voltage in her house wiring) but not all the time.
Regardless, I went ahead and gave her a 90W supply from our bin of lonely power supplies. That worked great.
Here is the perhaps useful information for anyone wondering and wandering.
She was running a Lenovo 410 and that required the 90W to be happy. I am running a Lenovo T61p and it has been working great with that 65W supply.
Perhaps that will help someone out there. Perhaps not.