Well, I'd say safe temps could be anywhere between 60-70 degrees Celsius on a modest overclock of 4.0-4.4GHz.
I would honestly suggest just going into the BIOS and changing the multiplier from 34 to 42. Then leave everything else as it was. Afterwards, save and exit the BIOS. Boot into windows and then run Prime95 for a few hours to make sure everything is stable. Also, monitor your temps while running Prime95 with this program...
Your hardware is overclock capable, so you can do it quite easily.
Also modern overclocking is mainly done through the Clock Multipliers, RAM isnt a factor in CPU overclocking anymore.
Just go into the BIOS, enter wherever overclocking or CPU options are. There should be the Base Clock (BCLK) and the Multiplier. Base clock should be at 1000Mhz, and the multiplier at 34 (Base Clock x Multiplier = Frequency, so 1000x34 = 3400Mhz = 3.4Ghz, which is stock settings). Bumping up the multiplier will get you higher frequency's. Go up 1 at a time, back into Windows, then run Prime95 while monitoring temps. If its stable and the temps are fine, rinse and repeat. If its unstable, add a bit of voltage, back into Windows, Prime95 and repeat till stable.
Note: When upping the voltage, the temperature will rise much quicker.
Safe temperatures depends on your perspective, I personally dont let mine above 70C. But anything below 90C should be technically fine.
Safe voltage is again how far you are willing to go. I have kept mine at stock voltage.
You can get the 3570k to 4.2, 4.3Ghz without changing stock voltage by the way.
You think so amuffin? What does that typically mean "very little power phases"?
Think of it this way:
Power phases are like highway lanes, the less you have, the more chance cars can get jammed in them. The cars can get jammed like traffic, because there aren't enough lanes for those cars to get to. In this case, car=clean power to the CPU, the more lanes you have the more cars you can carry, resulting in more clean power to the CPU!
More power phases=better stability, better overclocks, lower voltages, etc. etc.