Ok.
Once upon a time, there was a thing called the "
Microsoft Hardware Quality Lab".
In this magical place, people who worked for microsoft collaborated with hardware makers (and their driver dev teams), to help assure that their hardware and drivers worked as expected with the operating system. In addition to this, there was an in-house testing and quality assurance group to assure that the operating system *ITSELF* behaved as expected.
Sometime in 2014,
those things got cut back very stringently, and eventually vanished completely. So, what exactly *IS* a signed driver?
Well, in the days of yore-- it meant that the driver had been tested in the Microsoft Hardware Quality Lab, against test samples of the hardware, and that the driver works as expected. To validate that the driver has not been tampered with, a digital signature is calculated against it, and included in a companion .pnf file. If anything in the driver changes even in the slightest, this signature does not match, and the OS goes "NAUGHTY!" and wont install it. Under the new paradigm, since THERE IS NO TESTING BEING DONE IN A CONSISTENT OR STRUCTURED MANNER, all it does is assure that the driver has not been tampered with in some fashion.
Now... Let's say you have a somewhat old nvidia video card. It is no longer "Officially" supported by the latest driver package. (the nvidia software goes 'no, go F yourself, and buy a newer card!') However-- the driver *TOTALLY WILL* work with the card, and this new driver enables some new technology that you really want. If you were savvy, you could drop in the PCI_ID inside the .inf file, and manually install the driver, tell MS to go F itself when it complains about the non-signed driver, and BOOM-- Fancy features activated yo!
Nowdays? NO-- YOU ARENT SMART ENOUGH TO DO THAT! WE WILL MANAGE YOUR DRIVERS! WE WILL REINSTALL THE OLD DRIVER ALL THE DAMN TIME, HOW DARE YOU!
Then there's the whole "Whoops, we screwed up and released a buggy version of our driver (which was not caught BECAUSE NO STRUCTURED TESTING) to the signature program, but we released a working one on our support site-- It has not gone through the red tape to get signed yet--- and probably never will, because that's a costly process for us for a product that is halfway through its product lifecycle, and it is more in our financial interests to focus on the new model hardware and its driver."
So, you install the updated driver, and it works fine. But then-- MS goes "NOOO!! UNSIGNED DRIVER! WE WILL ***FIX*** IT FOR YOU!!"
And then your computer gets the old buggy driver again, and bluescreens happen.