Computer won't turn on
I'm building a computer for my parents for christmas to upgrade their archaeic thing they call a computer and i put everything together and it won't start up. Everything is connected right to my knowledge and i think it could be a bad mobo. Its technically my first build although i replaced nearly everything when i customized mine, so i'm not completely ignorant. I thought it might be the PSU so i swapped out the 420 watt psu that came with my old computer that worked fine with the 350 watt psu that came with the case... same results- An interesting note both PSU's make a high pitched hum when the switch is turned on and the cable is connected. No juice tho. I have reseated the cpu twice, all the pins are straight- its my old cpu from my computer that i upgraded and it worked fine the day i took it out. I have checked all the cables to make sure they are secure, and the PSU is set to the proper voltage on the back. I'm stumped- i ordered all parts from newegg and the packaging was fine- no dents and everything was brand new. I removed the soundcard-and left everything essential connected and tried powering up but still nothing. Does anyone have any ideas on what i could do or what i havn't tried?