What are you running to test stability? Intel Burn In Test is the best program to test for temps. Prime95 will give you temps about 10c lower than IBT. You need to check that. Run both of those programs along with CoreTemp for temps. 35-40c is too low for load testing and too high for idle, so IDK what your doing to get those temps.
There is no "optimal range" for these chips, all are a little different. 1.3v sounds a little high for 4.4Ghz but that's just the luck of the draw my friend. At 4.5Ghz my chip will run with 1.3v. I have mine set at around 1.38v-1.40v for my 4.7Ghz overclock. My guess is that if you have a fairly good cooler you will get around 70-75c in prime95 and 80-85c in IBT. Which is fine. As long as you are around those temps you'll be alright. Start worrying if you get up in the 90's. Low 90's aren't too bad but that's not what you want really.
Good luck with your OC.