You shouldn't have to worry about it normally though since the 1520 is still top of the line. But hey, I'm all for undervolting and underclocking.
Over-volt is usually meant for short time benchmarking or competitions, but a good 24/7 overclock is all about under-volt and overclock at the same time. A good 24/7 overclock is all about getting a faster CPU with less voltage/heat for daily usage.
A good batch of a 2.2Ghz CPU can run at 3.0Ghz with less voltage, theoretically. This little monster is fast, but a lot of more speed with less heat is always welcome.
EDIT:
I have a power-station rig for 3D rendering and simulations. It has 2 Intel Xeon X5650 CPUs (each with 6 core and 12 threads) that was originally running at 2.66 Ghz with 1.23 Volt. I have overclocked it to 3.8 Ghz with 1.20 Volt.
The rig have been doing heavy jobs with 100% CPU usage in several years, sometimes running at 100% non-stop for weeks, but still doing great with delivering massive CPU-power with less voltage/heat.
These CPUs are rated to handle up to 90'C heat, but they are running at 60'C under 100% load. That's what 24/7 overclock is all about.
What type of 3D rendering do you do ?
I've considered going Xeon. I currently have an i7, I try to squeeze as much juice out of the i7 as I can. Your temps are good !
I have been rendering Autodesk Maya and Blender 3D scenes, and a lot of scientific simulations too.
There is not much difference between a single Xeon and it's Core I7 contra part. Xeons tend to have better bindings and more reliability but a single-CPU Xeon won't perform much better.
But you need multi-CPU capable Xeons to build really high-power Multi-CPU rigs and these are really expansive. Besides Intel have recently locked the overclocking possibility on multi-CPU Xeons, and high-end CPUs will cost your shirt.
The Intel Core i7 "Haswell-E" processor will be out in Q4-2014, according to Intel roadmap. These will be a much better option for rendering rigs, with lower price and good overclocking capillaries.
I find my way around Maya, but that's a huge program and I don't know all it's tricks.
Yes, Haswell-E is around the corner, and current leaks/rumors sounds promising. It's defiantly worth to wait and see a few good tests before upgrading CPU.