PC wont start unless unplugged for 15mins or clear cmos

[FiagaiMor]

I bought a new pc about 2 weeks ago and it was running fine until it got turned off via the power button while I was in bios, now it won't start up unless I unplug it for about 15mins or use the clear CMOS button. I've reset the bios back to default and even switched to a second bios, but it still wont start.
I don't know what else could be causing it so any help or information would be much appreciated.

EDIT: holding the power button down for 10 secs didn't help and it runs perfectly after I plug it back in

OS windows 10 home
motherboard msi x99a raider
CPU i7 5930k
GPU 2 sli NVidia 980ti
ram 16gb 2800 ADATA XPG Z1
HD 512GB SanDisk X300 SATA SSD
Power supply EVGA SuperNOVA 850 GS 80 Plus Gold

 

[Ralston18]

Try replacing the button battery on the motherboard.

When up and running make sure that the time and date are correct on the system.

 

[FiagaiMor]

Try replacing the button battery on the motherboard.

When up and running make sure that the time and date are correct on the system.

 

[FiagaiMor]

Try replacing the button battery on the motherboard.

When up and running make sure that the time and date are correct on the system.

Sorry about how long it took to reply, I've been out of town.

Turns out the power supply was bad l. I took everything off the motherboard and hooked up a different psu and the motherboard worked fine