New system, weird not starting issue1

Hi, I am having problems with a PC I have built Asus h110m-k intel i5-6600k Kingston 2133MHz 8GB Samsung 750 evo 120GB SSD Toshiba 3TB sata3 HDD Asus drw-24d5mt dvd writer Unyka slim tower with 450W PSU All worked OK initially, then in the last 2 weeks it has not turned on correctly, the screen would power on and the Asus logo would appear but it would go no further.