Not sure I'd risk taking the GPU apart. Are you sure the GPU fan is clean and turns freely? And what about the chassis fan? Is it clean and turning freely? Launch the diagnostics from the F12 boot menu and run the fan tests. And grab some canned air and blow all the dust off the GPU, motherboard, CPU heat sink and its fan, case vents etc. I'd see if that helps before dissecting the RX480 card. On this PC model, the onboard video ports are disabled as long as an add-in video card is installed. So you have to remove the card to test the onboard video ports. There are at least 10+ threads about updating the GPU in the XPS 8910 so read some of them to see what GPUs other users have installed in this PC model.  
Hi, On my XPS 8910, which is up-to-date and running fine, I am planning on taking out the Dell original AMD RX 480 GPU and attempt to add new thermal paste to the GPU.  It has been running hot and causing the PC to run hot, etc.  In the event I break something, I was thinking about a backup plan.... If the GPU is NOT present, will the system automatically boot to the integrated video? If it requires a BIOS change, I can probably manage that. But please help with info. Followup question: I am likely going to buy a new GPU soon.  Nothing too wild as I am not a dedicated gamer and don't want to replace the power supply, etc.If I do buy a new GPU, do I simply remove old on, put in the new product and boot and the system will know the old GPU is gone and guide me through any installs of drivers or the software supplied software? Thx DD
Can I remove the AMD RX480 GPU and will the system boot to integrated video?