Re: PC not recognizing AC adapter although it is working well.

Hi Aatish,

Welcome to the Community,

System model Inspiron 5421 is offered with 65 watt and 90 watt AC adapter.If you're system came with 65 watt adapter you need not switch to 90 watt adapter.65 watt adapter will work on your system and it does not reduce the battery life.

Did you check in BIOS (tap F2 on start up,Dell logo),if the AC adapter is getting recognized normally(as 65 watt) or does it show "Unknown"?

Also on the  BIOS screen check and post back the BIOS version.

Thank You