Random Shutdowns, no idea why?! Please help!

[mondestine]

Hello all - 
 I've got an odd bit of an issue with my PC and I'm not sure what's causing it. It's a Ryzen build that I finished almost two months ago, and everything has been working great up until the past several weeks! In about the past two weeks, I've seen my PC just randomly, immediately shutdown while playing some fairly demanding games, like Hitman and AC Origins (This shutdown issue doesn't seem to happen much during non-gaming use). The keyboard and mouse lighting turns off, but the motherboard lighting, GTX 1070 lighting stay on, and the case fans continue to run as well - I've trouble-shooted virtually everything I can think of, and have no idea what's causing it.

 I've been using an overlay of MSI Afterburner & Riva Tuner to keep track of the temps and usage during games, and everything just seems to be fine? The coolermaster AIO keeps my CPU at low temps during idle, usually stays around the high 40's during games, with the occasional bump into the low 50's, and the cpu usage% seems to be normal as well. (To be safe, I did re-apply thermal paste, but I've never noticed any issues with CPU temps anyway.) The GTX 1070 seems to be running safely, with the ACX 3.0 fans keeping the temps in the mid to high 50's during most games.

So yeah - I really don't know what to say about why these random, occasional shutdowns have been happening, and why it is that the mobo lights/case fans continue to run as well.  I am using an EVGA 500W White 80+ power supply, but I've been under the impression that 500W is enough for a GTX 1070?

                Anyways, any guidance, suggestions or help is very appreciated!
                          Thanks so much, and a happy new year to everyone!

                   My PC build details:

                                        CPU:  Ryzen 5 1500X

                                       Mobo: Asus Prime-B350 Plus (I don't know the Bios update version right now, sorry.)
                                           RAM:  Ballistix 16GB DDR4 2400
                                        GPU:  EVGA GTX 1070 SC

                                       Storage: Kingston 256GB SSD, Seagate 3TB 7200 HDD

                                         PSU:  EVGA 500 W1, 80+ WHITE
                                            Fans: 4 Corsair AF120MM Quiet Blue LED

                                            Case: In Win 303

 

[Canada EH]

Power Plug securely inserted, each and every power plug, meaning the pc plug into plug bar and plug bar into wall.

Next up is do you have enough power in the power supply for all your items inside the pc. Like you dont have a 200W psu.