Monitor , mouse and keyboard not working

So today while I was playing a game my PC suddenly turned off , when I tried to open it my monitor mouse and keyboard where not responding.. I tried again n again with no succes. Weird thing is, when I changed my main tower with my secondary it did the same, so I assumed it was the keyboard monitor and mouse that had the problem, but when I plugged in different ones it would still do the same!!even with my secondary PC...I have no idea what happened or what to do..I need help asap.thanks