My PC only displays video through the motherboard now, and Device Manager only shows integrated graphics. The GPU lights still come on, but the Nvidia app can't detect the card.
I've reseated the card and its power connections and tried another PCIe slot. What else can I check?
Check whether the card appears in your motherboard's BIOS or UEFI, if it has a PCIe device listing. If it shows up there but not in Windows, that points more toward a Windows or driver issue. If it doesn't show up, the card, slot, motherboard, or power delivery become stronger suspects.
Not every BIOS makes that information easy to find, so an empty or unclear menu isn't necessarily a definitive test.
The lights only tell you that some power is reaching the card, not that it's getting everything it needs. With the PC shut down and unplugged, check both ends of the GPU power cables if the PSU uses detachable cables. Use only cables intended for that exact PSU model.
A PSU problem is possible, but the lights alone can't confirm or rule it out.
Since the second slot didn't help, the most useful next test is swapping hardware if you have access to it. Try the GPU in another compatible PC, or try a known-working GPU in yours. That can help separate a card fault from a motherboard or power issue without buying parts on a guess.
You don't have to rely on the Nvidia app for every driver check. In Device Manager, turn on Show hidden devices and see whether the card appears as a disconnected device. You can also get the standalone driver installer from Nvidia.
If the installer still can't find the GPU and the card isn't detected outside Windows either, reinstalling drivers is less likely to be the fix.
Answers are reviewed before publication.
walking_speed_only:
A hidden, disconnected entry can be an old record. It doesn't by itself mean Windows can currently see the card.