My MacbookPro6,2 was experiencing GPU Panics. There are a lot of reports with regards to Apple previously replacing the boards and after a little while, the problem reappears. I did a lot of research on this issue when my MBP started to crash (GPU Panic) 5-6 times a day.
Results from my research, the issue is the Tantalum capacitor used to regulate power to the dGPU. When the dGPU is running at high performance settings, it requires a lot more voltage. Because the bad capacitor can't handle the voltage anymore, it cause the GPU Panic.
Solution was to replace the bad tantalum capacitor; not just with a similar part! If you do that, you'll end up with the same issue later down the road. The solution is to replace the bad capacitor with a better part! Louis Rossmann recommended using Aluminum Polymer capacitor because they are highly reliable! Here is the link to his video (https://youtu.be/DzcgT_fiVTA) ... just don't mind the language used! I used a Panasonic Aluminum Polymer Capacitor (https://www.digikey.ca/product-detail/en...).
Since I had the logic board out of the laptop enclosure, I decided to clean and replace all the original thermal paste that Apple applied. Note ... it is quite the mess they've created! Using more than actually needed.
Last image highlights the Aluminum Polymer Capacitor I used in my fix.
Overall results ... no GPU panic since replacing the bad capacitor. MBP is running very smoothly.
My Mac: MacbookPro6,2; MacOS Sierra -10.12.2; 8 GB; 512 GB SSD; External Display - Dell U2713HM @ 2560x1440.