New power supply now computer won't turn on

kat3033

Honorable
Jan 22, 2014
2
0
10,510
Bought a new 500W power supply to replace the one of the same wattage. I wanted to replace the old one which might have been giving me problems. I put the new ps in and my computer turned on for 2 seconds and then shut off. I checked and double checked several times and all connections (to motherboard, cd/dvd and hard drive) are connected and secure. I put the old one back in, and my computer turned on. Again I put the old one in and the computer does the same thing as stated above. I now have the old one back and I'm able to turn on the computer with no problem. Can anyone tell me what the problem might be?