reset the bios, unplug everything except the cpu and memory, (hdds, usb ports, video card absolute last) if it won't try to power on, then the cpu is bad.
Sometimes it just happens, but its best to eliminate any outside interference just to make sure its isolated to only the cpu. My friend just set one up on an asrock, wouldn't boot up, found he had a bad sata cable after a day of wtf. But since your already running it with a sempermon, chances are more towards the cpu needs a warranty.
Edit: just saw this is your second chip. ...
is that 16 gb 4 sticks of ram? if so try with 2 or even 1.
Yes it is 4 sticks of RAM, I will try it with only one and the aforementioned suggestion, hopefully it works. Is it better to RMA from AMD or the retailer?