Cpu power strange

Hello,
So, my cpu just started to do something strange and I dunno how to diagnose it. I took it out of sleep mode and the monitor was showing flashes of the screen. Like the desktop would dissapear and flash. So I restarted it. Now the monitor won't read and it says it's on but it's dead quiet. If it wasn't for my LED lights coming on I'd never know it was on. It makes a small wirring noise upon starting but then goes quiet. My keyboard lights up and when I hit enter a couple times it goes dark so honestly, I don't know where to start with this.