So my E6750 is running at 3.2ghz (400x4) with 1.30v (shows in CPU-Z, in my bios it's 1.3250)
If I lowered it to 2.66ghz(stock) or 3.0ghz I can run both stable at 1.22V (shows in CPU-Z)
Is that normal? I mean that's a big voltage difference between the two speeds and the speeds difference is not that big. Also, between 2.66 and 3.0ghz (both at 1.22v) which one will produce more heat? or they should be about the same since they're both 1.22v?
Frequency makes minimal difference in power consumption if voltage remains the same. A change in voltage makes a large difference in power consumption, and therefore heat output. But to answer your question, at 3GHz it will run hotter, but likely no more than 1-2C hotter at the most.