If you have just installed a discrete graphics card (that didn't come with the system) into a prebuilt system with Windows 8 or above preinstalled on it and get no Video at POST or a beep code, assuming the card has enough power and is properly seated with the necessary power connections, a common cause of this issue would be a conflict with Secure Boot on UEFI motherboards.
We have created a short guide for different builds below. To fix this issue you will usually just need to plug the monitor back into the onboard video to get video, then go into the BIOS to disable Secure Boot.
If you wish to get the UEFI Firmware update for 600 series cards(models 640 and above) send us an email at email@example.com with your model number.
Please note that you would need to flash the firmware while in legacy mode by following the instructions below.
More information regarding UEFI support can be found here: https://nvidia.custhelp.com/app/answers/detail/a_id/3156/kw/uefi
With new HP computers either press F10 to get in the BIOS, or the Escape key to bring up the Startup Menu then select Computer Setup or BIOS Setup. There’s a menu on the Advanced mode side for “Security”. Under “Security” there will be a "Secure Boot Configuration" menu where you would want to disable both “Secure Boot” and “Fast Boot” and then enable “Legacy Boot Support”. When the options are set hit F10 to save and exit out of the BIOS Setup. The system will reboot and ask you to enter in a passcode to confirm changes. After the system boots into Windows go ahead and shut the system down and install the graphics card as normal. The graphics should now be displaying through the video card.
More information of the HP BIOS can be found here: https://support.hp.com/us-en/document/c03656066
The Gateway family, after entering the BIOS by hitting F2 or Delete, you will want to navigate to “Authentication”. Under Authentication you will see Secure Boot which you will want to Disable. Now, navigate over to the "Boot Options" menu at the top and enter in the "Launch CSM" option and set it to always. You may also want to verify that the "Video OpROM" is set to "Legacy" Once those settings are changed you will be able to save and exit. When the computer starts into Windows shut it down, and install the graphics card normally. The graphics should now be displaying through the video card.
For Lenovo desktops, press F1 or F12 to enter into the BIOS Setup. Under the tab "Security" there will be a "Secure Boot" menu where the only option in the menu would be to Enable/Disable Secure Boot. Disable the Secure Boot option and then move over to the "Startup" tab. Under the Startup tab, change "Launch CSM Configuration" to Enable, keep "Boot Mode" as Automatic, and change "Boot Priority" to Legacy First. While still under startup, change "Quick Boot" to Disable. With those settings changed, Save/Exit out of the BIOS. Once those settings are changed you will be able to save and exit. When the computer starts into Windows shut it down, and install the graphics card normally. The graphics should now be displaying through the video card.
With Dell brands you'll want to press F12 to enter the Boot Menu. Under the Boot Menu there will be the setting "Change Boot Mode Setting". That setting will have the option to turn UEFI Secure Boot On or Off, change it to Off.
More information can be found here: https://en.community.dell.com/support-forums/desktop/f/3514/t/19566955
Asus will be F2 or Delete to enter the BIOS setup. Switch to the Advanced Mode by pressing F7. Under the "Boot" tab you will see the "Fast Boot". Disabling will automatically change everything else. Next, go under "Secure Boot" and change the "OS Type" option from "Windows UEFI mode" to "Other OS". Once those settings are changed you will be able to save and exit. When the computer starts into Windows shut it down, and install the graphics card normally. The graphics should now be displaying through the video card.
Hit DEL key to enter BIOS. Under BIOS Features, go to PCI ROM Priority, change from 'EFI compatible' to Legacy. Also under Init Display First make sure this is set for PCIe Slot1, save and then exit.