Every couple of years, even with sometimes buying other systems, I tend to treat myself with a Titan Mobile Workstation. Hands down, the best laptops I've ever owned and can be ordered with insane/absurd levels of performance.
Anyhow, unless they've changed in the past 8 months, those can be ordered with no operating system.
They're pricey if you want them to be, but they're otherwise reasonable. Hmm... I'll get you a link. (I am in no way affiliated.)
Find the perfect blend of power and portability with Titan's mobile workstation computers. Ideal for the professional on the go, these systems don't sacrifice performance for convenience. Work wherever inspiration strikes with a Titan mobile workstation.
www.titancomputers.com
Play with their configuration tools and you can make 'em rather pricey. They're otherwise not too expensive for what it is. I've bought a few over the past decade and a couple of times I ended up with a laptop that was more powerful than the desktop I was using at the time.