1. Because I need the speed for tessellation in Metro 2033. >:D
2. It's a factory overclock. I didn't bother reading the details but supposedly based off my dad there's some sort of toggle mechanism. I'm not sure if it's physical or software.
Over clocking is done either through software or BIOS. BIOS methods usually have the best Overclocking ability.
That being said, if you've never done it before, I recommend you leave your processor at the current rate that it is. Its more enough with a decent graphics card to handle metro 2033. Tesselations IS handled mainly by GPU.
According to a google search, 4.3GHZ was Anandtech's attempt at overclocking it on air. You have to have a pretty big air heat sink w/ a good fan(s) to achieve this sort of thing, otherwise just pushing it to 4.3 with stock cooling will either cause your CPU to be unstable or it will just fry itself with too much heat. You would likely need a liquid cooling set if you were to even think about reaching this yourself
Overclocking can ruin/reduce your CPU life greatly if you don't know what you are doing
In short: leave you CPU as is.
