Up^2 with fan, Pentium N4200 crashing/rebooting Win10 with heavy graphics use

I have correctly installed Windows 10 Home on the Up Squared board I just received, and installed the drivers from the download section of this site. I'm using the power supply included in the dev kit for the board. I have replaced the passive heat sink with the active fan heatsink included in the dev kit.
With the fan, the CPU is running at under 60C, even under heavy load. Usually around 49C. I have the board sitting in the open, not enclosed.
The board idles fine, however when I run a graphics-heavy application (I am using my own software that rotates a 3D model on screen), randomly but after usually a few minutes, the system unexpectedly restarts.
I've triple checked the heatsink, thermal goop, everything is installed correctly, but it spontaneously reboots only when I'm pushing the GPU.
My intention was to use this board for a product that creates and displays 3D models, so this is a dealbreaker for me if I can't solve this issue.
Aaeon, anyone, can someone help?