Replacing a graphics card is among the easiest upgrades physically and among the easiest to get wrong at the ordering stage. The checks that matter happen before anything is bought.
Check these three first
Length against case clearance. Cards range from around 200 mm to over 350 mm. Case figures are usually measured without a power cable attached, so allow extra where the connector sits on the end of the card. Some cases recover length if a drive cage is removed; check whether the manufacturer quotes a figure for that configuration.
Power connectors. Confirm your supply has what the card needs. If the card uses a 12V-2×6 connector and your supply has no native cable, the supplied adapter works but needs each input run from a separate cable, and the assembly is bulky enough to affect side panel clearance in a compact case.
Supply capacity. Follow the card manufacturer recommendation. Our calculator estimates your total draw, and the PC Builder checks all three of these against your existing parts.
Also worth checking
Slot width. Many cards occupy three slots. Confirm you have the space and that nothing else needs the slots below.
PCIe generation. Mostly unimportant, with the exception noted in our PCIe guide: a card using only eight lanes in an older PCIe 3.0 board loses real bandwidth.
Whether the processor can keep up. If your current card already sits well below full utilisation while gaming, a faster one will not deliver what you expect.
Doing it
Shut down and switch off at the wall. Unplug the display cables. Remove the side panel.
Unscrew the bracket, press the retention clip at the end of the PCIe slot, and lift the card out evenly. The clip is easy to miss and easy to break by lifting without releasing it. On a long card with a large cooler it can sit under the shroud where you cannot see it; feel for it rather than pulling harder.
Fit the new card until the clip clicks, screw the bracket, connect power, and connect the display to the card rather than the motherboard.
Heavy cards sag over time, which stresses the slot. If the card came with a support bracket, fit it. If not, a simple anti-sag support costs very little and is worth having on anything with a three-slot cooler.
Drivers
Moving between cards from the same manufacturer usually needs nothing: the existing driver recognises the new card and continues.
Moving between manufacturers is cleaner with the old driver removed first. Do that before swapping the hardware, while the old card is still installed, because removing a driver leaves you at a basic display resolution until the new one is in.
If you see stuttering or odd behaviour after a swap that otherwise went well, a clean driver removal and reinstall resolves most of it.
What to do with the old card
Do not throw it away. Even a card several generations old has resale value, and that money reduces the effective cost of the upgrade considerably.
Before selling, run a demanding game for half an hour to confirm it still works properly, and clean the dust out of the heatsink. Both are reasonable to do for a buyer and both improve what you get for it.
Keep it if you have a second machine, or as a diagnostic spare. Having a known-working card makes diagnosing a future display fault straightforward.