Is there a reason to up the voltage if things are stable?

[syvmn]

Brand new OCer here. I've been tinkering with my i5-3570k a little bit and have a couple of questions including the one in the title.

Specs:
i5-3570K
212 evo cooler
ASRock z77 Extreem4 MB
8gb Ballistix DDR3 1600 memory
Thermaltake v3 black edition case
Corsair TX750w PSU

1. I just set the multiplier to 42 (4.2ghz) at a fixed 1.10v and ran prime95 for 10 minutes. Max temp was 61C. I guess I just expected this to fail because people talk about running at 1.25v and higher but mine (in the short run) was fine at 1.1v. Is there any advantage to running higher voltage if this 1.1v ends up being fine in an 8 hour prime95 test?

2. I saw some people suggesting setting the offset voltage instead of fixed voltage. Are there pros/cons to this?

3. Are there any settings in the bios I HAVE to change when overclocking, or is the multiplier/voltage settings a good place to have a go at it?

4. One of my cores consistently runs 5 degrees C cooler than the other 3. Is there any point it cranking that one up by itself since it can handle it, or is that making things complicated?

5. My ram shows up at 800mhz in CPU-Z. Is that just because it is dual channel, so 800x2=1600mhz?

Any other advice you can give me would be extremely helpful. I don't want to OC as high as I can, I would just like to OC to a very comfortable level.

 

[syvmn]

Update: I just set the multiplier to 44 (4.4ghz) @ 1.1v and ran prime 95 for a half hour. Max temp 66C. I feel like I'm missing something. Why are people running @ 1.25v?

 

[amuffin]

Some chips are different, you might have gotten a better chip than others that can be stable at lower voltages.

1. You can ensure stability by running a slightly higher voltage than you are currently.
2. Offset voltage allows your chip to run at much lower voltages when it is idle, instead of being at a constant voltage like it would be underload. When the chip is underload the voltage will bump up to the voltage set. It's a bit of guess and check in this case .
3. CPU power, etc.
4. There will always be variations in core temperature.
5. That is correct.