Computer screen not turning on and no motherboard post

[techynoob7]

A few days ago my computer decided to turn off randomly and not turn back on. I thought it could have been the power supply so I installed my older one. It didn't work so I thought it could be the motherboard that was causing problems. After putting in a new battery into the motherboard after a recomendation, it decided to turn on. I also plugged it directly into the wall where previously it was plugged into an extention cable. The only problem now is that my monitors aren't displaying anything. When I try holding down the power button to turn it off nothing happens. Are there any suggestions about what could be causing the problem? My motherboard is over 5 years old now and it was probably only worth $40 -$50 when I first got it. I also got no motherboard post when it turned on.

New powersupply- EVGA superflower 750 B2 (got it 6-7 months ago)
old powersupply- corsair cx 750m

 

[smorizio]

if your mb and cpu have onboard video pull the gpu see if anything posts onto the screen. if it does try one gpu see if the gpu comes on. if there nothing on the screen with the old gpu try the gpu in another pc or see if a test gpu works in your pc.

 

[techynoob7]

if your mb and cpu have onboard video pull the gpu see if anything posts onto the screen. if it does try one gpu see if the gpu comes on. if there nothing on the screen with the old gpu try the gpu in another pc or see if a test gpu works in your pc.

I don't have onboard video (igpu if I'm not mistaken). I tried reinstalling the gpu and got nothing. I could try reinstalling my gtx 970 but I don't want to risk frying it. I was planning on upgrading my motherboard cpu and RAM to the new coffee lake stuff but it looks like I will be upgrading sooner if this problem isn't resolved. I think I might reinstall the other powersupply since I somehow got it to turn on.