Intel NUC boards - Four-by-four inch Intel NUC boards come with a soldered-on processor.
System76 Oryx Pro - System76 Oryx Pro is a powerful and customizable laptop that comes with Linux pre-installed, but y can easily install Window and dual-boot if you want to use it for Windows development or gaming.
ESPRESSObin - Electronics, Single Board Computer, and x86
Dell Precision 7730 - Very robust 17" workstation with flexible configuration options, the cheapest display is not recommended however. Read review here.
Udoo x86 Ultra - Udoo x86 Ultra is a modern PC, known as the most powerful X86 maker board and an Arduino 101 compatible platform.
HP ZBook 17 - The performance of a desktop with the freedom of a laptop.