I was getting bored with my XP box one day, so I decided to try some of the answers to this question to see if any of them would cause a BSOD.
They didn't, and they seemed like they would be the most likely to do that, so I was wondering if it is possible to trigger a BSOD from user-mode in C/C++, and if so, how?
It seriously difficult to make a BSOD from user mode unless the user mode program interacts with buggy drivers (may be a particular sequence of operations can reveal the bugs in particular driver) disturbs the driver stack. From user mode, the inputs are validated well before passing to the kernel mode to ensure the stability of the system. Most of the Microsoft API/Drivers have validated well to avoid security issues in the system; so does the driver manufactures.
The best way is to disturb the driver stack, but it's not user mode.
You can create BSOD with NotMyFault SystInternals utility. It fundamentally injects a driver and create the BSOD