How much of a performance loss will there be without the video drivers?

[PCNoobXCVII]

I have a new MSI R9 270x and for some reason it's rejecting the video drivers but accepting the rest. So exactly how much performance will I lose without the video drivers if I try to game on it?

 

[PCNoobXCVII]

until you have the money, use the GPU sans drivers.

Sans drivers? Sorry for my lack of knowledge but what are sans drivers? Are they just the stock drivers?

Meaning "without drivers"

Okay, thanks.