This is probably the best guide to follow:http://www.overclock.net/t/1348623/amd-bulldozer-and-piledriver-overclocking-guide-asus-motherboard
Yes, you don't have an Asus board but most settings should be the same or just named a little differently, you can always google the setting you don't understand or ask here for help with it.
1.425v to me seems like a lot just for 4.5ghz, i know every chip is different but my 8320 did 4.5ghz well under 1.4v, can't remember exactly voltages for 4.5 but it did 4.2 at 1.3v.
I would start from scratch, reset to defaults and move up from stock speeds/voltages slowly.
I also suggest using AIDA64 for stress testing rather then Prime95, it puts a more realistic load on the cpu, plus you can monitor temps/voltages all within the same program.