Hello,
It would be beneficial to us if we knew your entire system specs. If your computer is retail, then we need the manufacturer, series, and model number. For example, my old desktop was a "HP Pavillion a6110n". If the computer is custom build, please provide us with a list of every single part, both the maker and the model number.
First, make sure that the graphics card is connected correctly. Find your video cable and make sure that is connected and make sure that both screws on each end are entirely screwed in. You don't need a screwdriver, finger tight screws is good enough.
Try re-seat the graphics card. Power down your computer, take the graphics card entirely out of the slot, make sure that no dust or any particles are on the graphics card connectors or in the slot. If the slot has something in it, you can use compressed air to get it our, or a vaccum cleaner hose with a narrow attachment.
After re-seating the card, make sure that the power connectors are connected securely. If your power supply is modular, make sure that all of the connectors are connected to it securely as well.
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