A GPU that is physically installed but not appearing in Device Manager, or one where the display is working through CPU integrated graphics rather than the discrete card, can have several causes. The systematic approach below identifies the root cause without wasted parts-swapping.
First Checks
Verify the physical installation. The GPU needs to be fully seated in the PCIe x16 slot — the retention clip should audibly click. GPU PCIe power connectors must be fully connected (most GPUs require 8-pin or 16-pin power connectors from the PSU). A GPU without power will either not work or work only at reduced capability.
BIOS/UEFI Check
Enter the BIOS (usually Delete key on boot). Look for PCIe configuration settings. Some motherboards have a setting for "Primary Display" that may be set to CPU Integrated instead of PCIe. Change it to PCIe/PCI or Discrete GPU. This is a very common cause of the monitor displaying from integrated graphics while the GPU is ignored.
Windows Device Manager
Open Device Manager and check under Display Adapters. Options:
- GPU is listed with a warning icon (yellow exclamation): driver issue. Right-click → Update Driver, or use DDU (Display Driver Uninstaller) in safe mode for a clean driver reinstall.
- GPU is not listed at all: Windows is not seeing the hardware. Check under "Other Devices" for an unidentified device.
- GPU is listed as "Microsoft Basic Display Adapter": driver is missing. Install the appropriate NVIDIA or AMD driver.
PCIe Slot Issue
If the GPU works in another system but not your own, the motherboard's PCIe slot may be damaged. Test the GPU in a different PCIe slot if available, or test with a known-good GPU in your primary slot.
PSU Adequacy
An underpowered PSU may not supply enough power for the GPU to initialise properly. Check that the PSU's rated wattage covers the system's total power draw with 20-30% headroom. A failing PSU may also cause GPU instability without being obviously insufficient.