Hello its been awhile but you guys know your stuff. i have a amd iix3 435 with an asus m5a78l-m lx and it has core unclocker. when i unlock the 4th core it goes into like a loop it will begin to start windows but restarts and like i said its like a boot loop. i play some games on there but watch alot of movies so i know if oc or unlock which is better and reason for crashs. thought it might be voltage but i cant figur out howto change it.
When you attempt to unlock a dormant core, you are always risking unlocking a defective core. That is one of the reasons they are disabled. Sometimes they work as good as the other cores, sometimes they work but are unstable, sometimes they don't work at all. From your explanation, it appears your dormant core was defective, hence the reason it was marketed as a triple core rather than a quad core.
You can try messing with voltages to get it stable though to be honest if it was unstable off the bat it will likely remain that way. Better off to OC the 3 cores as far as you can your uses dont really demand a 4th core anyway.