Question PC running but no mobo and on

Mar 18, 2019
I have an hp pavilion p7-1423w. It has been well taken care of always cleaned, virus scans, etc. Everything is stock. i5-2320. The only thing new is a 4 GB ram stick & a nvidia geforce 1050 video card, both installed early last year. My pc has worked flawless all this time. All the sudden last week it was acting real choppy during regular use so I restarted it. Upon the attempted restart it was acting really display, no beeps, no post, fans would run then shut off repeatedly then just sit there running the fans, no hdd lights, no mobo light, no display still. After researching and troubleshooting from guides online, I thought I had a bad mobo. I bought a new mobo from ebay, installed it and my pc booted right up with display, no mobo light still. I left it on and left the house. When I came back it was messed up again all the same symptoms exactly. Tried troubleshooting over and over but nothing. I reinstalled old mobo and nothing. I tried new video cables, new power cable, different wall outlet. Then today I powered it up just to see and it's working again, I'm on it right now. There still isn't any mobo light however. I don't know what the problem is. I tried my son's 1050 and his Corsair psu and my pc still wouldn't work with his stuff. What do you guys think? I'm pretty sure this pc will mess up again.