Can pull off 65W from a 90W?

My laptop originally came with a 90W power adapter and I accidentally left it in me dorm room. I found a 65W power adapter by the same manufacturer but upon boot-up, I got a screen that said it was inefficient. Am I safe with using the 65W one for the weekend, including playing games or do I need the 90W one?

I actually got the same message on my Dell for some reason, as long as you don't notice anything wrong and it's only temporary then I wouldn't worry about it for long.

It works on an HP laptop.