TEMP and OC?

Does temp effect the oc at a certain voltage.

Say you're stable at 2.1ghz at default volt but at 2.2ghz you're not stable. Would the temp make it stable if it was say -40c?

It depends. If you are getting over 50C and you can't push it any more, then lower the temperature may help you to push it higher. It's just one example. Every CPU should have a different max unstable temperature.

Also most people who use extreme cooling are for using higher voltage to make the CPU stable while not taking damage from high temperature. Well on the other hand voltage can damage CPU without high temperature.