White light is defined as the color of light made from all wavelengths of the visible part of the electromagnetic spectrum at the same amplitude. So yes, it will always produce a continuous spectrum, because that's what it is.
However, we can make colors that will only split into 3 or 4 single wavelengths of light, that will look like white to our brains. This doesnt fit the above definition of white, bout our brains will still say it is the same color. Scientifically, we wouldnt call that color white, but it's the same color.
So, in short yes you can, but it's a different type of white light
In lighting, they have another definition of white, it's defined as the blackbody spectrum of a body at high-temperature. If you fiddle about in your monitor settings, you should find a way to change the color temperature. This changes the color balance from a black body at different temperatures, colder temperatures look slightly blueish, warmer temperatures look slightly reddish, but it's still defined as "white" from the lighting point of view.
Linear Mode
