Not every story has a happy ending. In 2018, a flawed PCI Express Root Complex driver from a major OEM caused random DPC watchdog violations on Windows 10 laptops. The driver would hold a spinlock too long while enumerating PCIe devices, freezing the system for milliseconds—enough to trigger a blue screen. Users had to roll back to the generic Microsoft driver until a fix arrived.

– The SSD jumps to full speed. More importantly, Alex notices that the system now reports PCIe Link Speed correctly (Gen4 instead of Gen3) and enables Active State Power Management (ASPM), which lowers temperatures by 5°C.

Let’s follow a real-world case:

When you first install Windows 10 on a modern motherboard (Intel or AMD), the OS loads a generic PCI Express Root Complex driver. This driver knows the rules of the road : how to configure bus numbers, assign memory addresses, and handle interrupt requests (IRQs). But it’s a little like a substitute teacher—competent but not intimate with the classroom’s quirks.