If you are idling at 19C you must be in a walk-in refrigerator. Which program is telling you that?
In any case, 4GHz D0 with a TRUE is not too difficult. I have mine running at that speed with 1.23 Vcore. It peaks with 8 thread prime 95 load at just under 70C. I'm using a P6T, but I'm sure you can get similar results.
If you are familiar with overclocking, just have at it. If not, you can check out this guide.