System hardware specs?
Especially PSU: make, model, wattage, age, condition?
You mention "gaming" and "monitors" (meaning dual monitors).
So my sense of the matter is that you are running a higher end system with components that either exceed the PSU's ability to support the corresponding power requirements or the PSU is beginning to fail.
Especially if the failures occur only when you start up a game. For example, GPU power requirements may be pushing the limits of the PSU.