If you are not overclocking and just looking for lower temps it would make sense to lower your vcore.
It is hard to say for sure how low your chip can go but I would think it would be stable in the 1.1-1.2V range.
Just for reference, my G0 Q6600 is 100% stable at stock speeds 1.1V.
Start there and test with
prime95.
If it fails @1.1V, bump it one notch and retest.
Repeat until success.