Getting the case documentation is the best choice. But if that's not available then you'll just have to figure it out. The case on the left can be opened by pulling the latch aimed at by the green arrow.
That's the sort of thing you find with an easy-to-open case. There's a nice, convenient latch just asking to be pulled. Once you pull the latch you can remove the door and get access to the inside of the machine. When people are having problems opening a case they often start removing screws that they should leave alone.
The bottom image shows you some screws aimed at by red arrows. Those screws hold the power supply to the case. Most cases have four power supply screws. Don't remove them unless you'd like to have your power supply rattling around inside your case.
The antique case in the middle note the 5. You can see a closeup of a thumbscrew in the bottom image. You open this kind of case by unscrewing the thumbscrews there may be more than two and then lifting the metal cover off of the case. The case on the right is a low-profile case sold by a large computer manufacturer. I think this one was designed by Rubik. Apparently, he felt that the cube was too easy to solve so he designed this thing Well, that's what I heard anyway.
The first thing most people try is to remove the thumbscrew in the back. In this particular case, the thumbscrew actually holds down the expansion cards and doesn't open the case that Rubik guy is tricky!
This is a good example of the hard-to-open school of thought. There's no obvious way to open the case. Usually there's a panel which has to be pushed or something which needs to be squeezed or pryed before you can pop the thing apart. This is when you definitely need the documentation. For this particular case, you have to push the "magic panel" aimed at by the green arrow towards the back of the case.
Then you can pop off the side panel. Remove your video card from its expansion slot Before removing the video card, make sure the computer is fully turned off. That sounds obvious but it's actually not as simple as you may think. Modern computers use an ATX power supply.
When you press the power button on the front of the case or shut the computer off from Windows, the computer appears to turn off.
But an ATX computer isn't really fully off. It just looks like it. Most of the power shuts down but an ATX power supply is still generating a standby voltage which powers parts of the motherboard. You can usually fiddle around inside a computer with only the standby power running but it's not a good idea. It's better to turn the computer fully off. Many motherboards have an LED which is lit whenever standby power is applied to the motherboard to remind you that it's not really off.
The way to turn it completely off is to use the power switch on the back of the power supply. Most power supply switches have a "1" for on and a "0" for off. Switch it to off 0. Then wait a minute or press the power button on the front of the case if you're in a rush. That will turn the power completely off. Some power supplies don't have a power switch on the back in which case your only option is to unplug the power cord. It's better to leave it plugged in so your case is connected to earth ground but you only have that option if the power supply has a switch.
Now make sure you keep your static discharged as described earlier. For most of you that means touch a bare metal part of the case with your finger.
Locate your video card. If you're not sure which one it is then trace the cable from your monitor to the video card. Unplug the monitor cable from the video card. You may have to unscrew a couple of bolts on either side of the monitor cable before you can remove it.
Some people screw them in to keep the monitor cable from accidently popping out of the video card. Most cases hold the video card into the case with a single screw. The red arrow points to it in the image above. Unscrew it if you have one.
Some cases don't use screws. Instead, they have a retention arm which holds the expansion cards in place. There's usually a lever which allows you to move the retention arm and get at the expansion cards. Consult the documentation for your computer if it's not obvious how to do it. Now you have access to the top of the video card but don't remove it yet. You've got to check for retention mechanisms. You have to unlatch them before you can remove the video card.
They're designed to keep your video card from popping out of its expansion slot during shipping. Some of them also help push the video card out of the expansion slot when unlatched. They're always at the front of the expansion slot. Some video card slots don't have a retention mechanism. If you have one then you'll need to unlatch it. Some of them twist. They tend to vary quite a bit so you'll need to look carefully to figure out what type you've got.
The most common retention mechanisms have little levers which need to be pushed towards the motherboard to release the video card. The image on the left shows the position of the latch when a video card is latched into it. You have to push the lever towards the motherboard to unlatch the card. The image on the right shows it in the unlatched position. Once it's unlatched you're ready to remove the video card.
Before you remove the video card you have to look for auxiliary power cables. Some video cards use too much power to get it from the expansion slot so they need an auxiliary power cable. Unplug any auxiliary power cables from the video card.
The video card shown above uses a floppy cable. Some high-end video cards even need two auxiliary power cables. The cables usually connect near the front of the video card like the one shown above. The expansion slots which hold video cards are often very tight which makes it difficult to remove the card. The easiest way to remove cards is to move the front of the expansion card upwards a little and then move the rear up a little.
Then go back and forth alternating between front and rear until it comes out. That minimizes the stress on both the video card and the motherboard. Try to avoid touching anything other than the edges of the video card or by the rear metal bracket. Some retention mechanisms will push the front of the video card up a little when you release the mechanism. If not, then you can start the video card moving upwards by sticking a finger below the front of the video card and pulling up a little.
Be careful not to bend any components on either the video card or the motherboard while doing this. There's lots of little electronics thingies sticking up from both mostly electrolytic capacitors and they don't like being pushed. The rear of the video card can be started upwards by sticking a finger underneath the rear of the card and pulling. Or you can push upwards on the video connector sticking out the back of the video card. It may take quite a bit of force to get a video card moving but they come out very easily once they've moved up a little.
If you have to pull hard then hold the top of the card with your other hand to make sure the card doesn't come flying out. Video cards and motherboards are not built like tanks. Once the expansion card is out put it into an anti-static bag if you have one. If you're installing a new video card then you can use the one which it came in. Insert your video card into an expansion slot First you need to pick your expansion slot.
This motherboard picture shows what the various slots look like. If you're installing a PCI card then there are probably a few to choose from. There are slight differences between PCI slots they use different interrupts but the video card should work in any of them. If you have one of those dual PCI-Express x16 motherboards then you should consult your documentation on how to install the video card.
There are usually restrictions on which slot to use if you only have one video card.