" required to disable the onboard video prior to installing the new video card." This hasn't been an issue for over 15 years. Secure Boot off in bios under F2 bios setup security has been a known issue since 2012 for NON DELL VIDEO Cards and legacy Video cards without UEFI Bios.  You shut secure boot off BEFORE installing the video card or it wont post. [URL]    
Trying to gain information regarding installing a video card. My questions are:      1.) Is it necessary / required to disable the onboard video prior to installing the new video card. The card selected is an EVGA GeForce GT640 and doesn't require additional power. It is a dual slot PCIe short card. Personally, I don't believe this is a requirement (PC built Oct 2019), but do appreciate other comments and thoughts.      2.) Given the information in item #1 above, is it a requirement to disable the secure boot in the BIOS since the graphics card may be identified has and unauthorized device. I've seen to many videos / comments that glance over this issue and fail to truly provide salient information. Thanks in advance for thoughts and comments regarding these two questions.    
Inspiron 3670 - Onboard Video - GPU Card