Do I have another bad psu??

[jackspeed]

I bought an antec 750W high current gamer bronze certified
antec 300
I have an i5 2500k
a gtx 460
a MSI P67A-G43
8 gb of ram

I assembled this in early august. Then around 2 weeks ago my power supply died I went to tech services in my school and they confirmed it was dead. I just received a new(refurbished) psu. I put in in my computer and I plug all the cables in. I turn on the computer after this when I hear a grinding noise coming from the power supply so I use the switch on my case to power my computer down. It almost powers down then it starts back up. I power down again and when it gets close to being unpowered I flip the switch on the back of the psu and it still powers back up so I use the switch on the front of my computer to power it down and then I have unplugged it.

Is it my psu? was it a mistake to go with antec? any assistance would be appreciated

 

[jackspeed]

I believe so but my question is how could it be a mistake by me if the power switch on the psu doesn't work?

 

[jackspeed]

I plugged in the cpu chord to the cpu socket.