I, too, own a Pavilion dv6, and after much work, I have figured out the problem, as well as how to permanently fix it. I believe the problem is a design flaw that is simple in nature, but difficult to find and fix.
Now, first let me explain how cooling works for the dv6. The computer's fan is hooked up to a series of flat copper tubes, which then pass over the CPU, Integrated VPU, and the additional Video Card if you have one. The purpose of the copper is to efficiently conduct heat, which the fan then removes from the computer via airflow. In order to ensure that the heat exchange between the chip and the cooling system is maximally efficient, the contact area between them is filled with a layer of thermally conducting paste.
That's the theory, anyways. But when I took apart my laptop (and my father, who also has a dv6, found the same thing when he took apart his), what I discovered is that the Integrated VPU and the heat ducts had too much space between them. Evidently, HP also noticed this, so they made up the difference by sticking a square piece of material between them so that they're in contact.
Now, in order for the VPU to dump heat properly, the padding in this space would have to be comprised of metal and thermal conduction paste. However, what I actually found there was a square of soft, heat-insulating silicon. The same was found in my father's laptop, and if those in this thread were to take their laptops apart and look at the heat conduction system, they would probably find the same thing.
So how to fix this? What I did was to remove the square of silicon. I then sawed off an appropriately-sized piece from an old heat sink and used that to make up the gap, sealing both the top and bottom with thermal conducting paste. DO NOT forget to scrape off the old thermal conducting paste they already used for the contact area of the CPU and non-integrated VPU (if you have it) and replace it. That stuff has to be replaced every time you remove the heat conduction array. Also, don't add too much paste; a thin uniform layer across the chip's black contact square is enough (it's a good idea to spread it thin with a thin, flat blade). Make sure the paste doesn't touch anything outside that contact square. That stuff's highly conductive, and it'll short any circuit it touches. I accidentally smeared it because we'd added too much the first time we took it apart, and we wound up spending ages cleaning it off the CPU and Video Card. Once you've got the CPU, Integrated VPU, and Non-Integrated VPU properly sealed, reconnect and reassemble the laptop.
Both computers, after implementing this fix, now run like a dream. Temperature doesn't exceed 70 degrees, and it only gets up there on a spike. The fan runs pretty quiet, and the computer doesn't produce anywhere near the heat levels that used to make it spontaneously shut down.