I repaired a DV2810us following the method described by Adolfo and it worked great. After covering the board in aluminum foil and only exposing the video/chipset chip, I used the heat gun on low ~700F for about 40 seconds. Hellus also had a good suggestion that I did and that was to replace the thermal pad with a copper shim. A very, very thin layer of AS5 finished it up. IMHO I would not run any kind of processor with out a heat sink since you cannot control the temps and any damage will start internally and it will be too late by the time you see it.

I have a C700 that had this same problem except it was the PQ2 chip. I tried to replace it without success. I had read others having luck just bypassing the chip with a jumper. I tried this and the laptop has been running fine now for a couple of months. I would recommend using the correct replacement if possible.