Question Problems after replacing power supply

[Pcox2006]

Bought a prebuilt system and power supply went out. Just replaced it with a evga 450 bt which powered up the computer again, but now the mouse and keyboard won’t power on and the monitor isn’t recognizing the computer. The monitor says in sleep mode no matter what I do. We unplugged everything and powered down. Rebooted. Tried various USB ports. Nothing works. Very new to computer gaming, can anyone give me suggestions? Greatly appreciated

 

[rgd1101]

make and model of this rebuild? sound like you miss a power connector on the motherboard

 

[Pcox2006]

The computer was actually bought for my son (im mom). I bought the ibuypower WA563GT2 desktop with AMD FX-6300, GT1030 2GB, 1TB HDD, 8G DDR3, and Window 10. The power supply was solytech 400 and went out after just one month. Had a friend tell us it was probably a motherboard, which we sent in and they tested. The company said the motherboard worked perfect. Then we bought the new power supply. The computer came on right away, just can't anything else to work.

 

[lynx1021]

Did you hook up both power cables to the motherboard, 24 pin and 4 pin?