Good point Furen! Make sure you have dropped the HT multi from 5x to 4x.
On voltage 1.45v is pretty conservative, I wouldn't hesitate going up to 1.5v-1.55. But I'm pretty hard core and upgrade every 18mos or so, if you plan on keeping your rig for several years 1.45v is safer.
I will say however, I've been doing this quite a long time and overvolting past what many consider safe and have yet to kill a CPU. I've still got an old athlon tbird 1.4ghz CPU that still works fine that I overvolted 20% and it ran that way for 7yrs before I took it out of daily service.
I usually take the volts up to the point of diminishing returns. When a CPU gets near its max it gets to where it takes more and more volts just to get a small mhz increase. I try and find that point and settle just below that.
Another utility that I really like for AMD CPU's is "RMclock" when used in conjuction with "cool n' quite" enabled in bios it allows you to throttle your overclocked CPU based on CPU usage. When setup properly it drops the CPU multi and volts when the CPU is idling (90% of the time when web surfing,etc...) using less electricity and putting less stress on the CPU. Then instantly ramps up to the max multi and voltage when you launch anything CPU intense. Kind of the best of both worlds IMO. It takes a little tweaking to find the best min/max settings to use, but well worth in IMO.