Video cards (also known as 'graphics' cards or graphics adapters) are the part of the computer that convert the digital data to analog (and sometimes digital) video. As was mentioned earlier, some motherboards have integrated video processors but those video processors are typically only good for basic computer operation and for playing simple games. If you want to play high-end computer games (World of Warcraft, Call of Duty, Grand Theft Auto, Splinter Cell, Half Life 2, Crysis...) or if you want to reduce the load on your processor, you will need a better video card. The following image is a relatively low end video card but it's significantly better than the typical integrated video processor. THIS one is a mid-range graphics card (in March of 2010).

Video Connectors:
In the image above, you should notice a couple of things. There are 3 connectors on the end panel. On the left, is a DVI connector. This connector can be used to drive the digital input of a monitor. This is the same connector you'd use with a High Definition TV monitor. The left-most connector can also be used with a standard computer monitor through an adapter. The center connector is used to drive an S-video OR composite video input of an analog monitor/TV. The right-most connector is used to drive a standard computer monitor. Basic video cards have only the blue connector. Recently, more motherboards have been offering more options for graphics output. Some have DVI (HDTV with/without the audio, depending on the board) and HDMI output.

You should also note that this is a 'single slot' card. This means that it only takes up one expansion slot. Larger cards take up two slots and can be more difficult to fit into some cases.

Note: The composite and S-video output signals are fine for watching videos or movies. They are, however, not suitable if you want to use a large TV as a second computer monitor. The resolution of a TV is far below that of a computer monitor. The display of the computer's desktop on the TV will be very difficult to read. If you want to use your computer with a television monitor, you'll need one with DVI or HDMI inputs.

Cooling:
In the image above, you should also notice that there is a heatsink on the video card. The heatsink is there to cool the GPU. The GPU (graphics processor unit) is similar to the microprocessor on the motherboard but is specifically designed to process video signals. Like the CPU on the motherboard, the GPU produces heat. The more intense the graphics, the more heat is produced. Since this video card doesn't have a really powerful processor, a simple heatsink will keep it cool. On more powerful video cards, you will see larger heatsinks and fans to keep them cool.

Memory Sharing:
When you have a graphics processor integrated into a motherboard, you have to share both CPU power and memory. With a dedicated video card, there is no need to do either. Most integrated video cards share at least 32MB of system memory. More commonly they share 64MB of system memory. High end 'gaming' cards often have 1000 MB (1GB) of memory. In some of the better gaming cards, the memory is optimized for video.

Memory:
This tells you what type of memory (DDR, GDDR2, GDDR3, GDDR5...) and the quantity of on-board memory. DDR is Double Data Rate. GDDR is Graphics Double Data Rate. It means that it's optimized for graphics.

Effective Memory Speed:
This tells you the rated memory speed. It can sometimes be confusing due to double data rate memory. DDR memory is rated at twice the clock frequency.

Chipset/Core Speed:
This is the clock frequency of the GPU.

Ports:
This tells you what type of signals it can deliver. The common outputs are S-video, composite video, standard VGA output and DVI out. Some also have input ports.

Maximum Resolution:
This tells you the absolute maximum resolution. The specs usually include refresh rate, color depth (in bits) and the screen resolution. A common spec for resolution may be 2048x1536@32bit color at 85Hz. This tells you that it can produce a display of more than 3 million (2048x1536) pixels at a rate of 85 frames per second. 60 frames per second is generally enough for most people but a few find that the image seems to flicker a bit so they may opt for a slightly higher refresh rate 75Hz or 85Hz).

Auxiliary Power Connectors:
On some high-end graphics cards, there is a need for an extra power connector because the slot in the motherboard can not supply enough current. If the card is driven hard and the auxiliary power connector is not used, the card will likely crash or shut down.

Video Card Connectors:
The following video card is very similar to the card at the top of the page. The main difference is that the card at the top of the page uses a PCI slot and the video card below uses an AGP (Accelerated Graphics Port) slot.

Below, you can see the difference in the connectors. The AGP card is at the top. You can see that the AGP card has many more contacts for a given area. If the AGP card is not fully seated, the card will malfunction.

The next image shows the AGP card latch/ejector lever. It assures that the card is always seated properly.

Although video cards are still available for AGP and PCI slots, PCI-E has become the new standard for graphics cards. The following shows the terminals for one such card. As you can see, they are different from the PCI card above. PCI and PCI-E are not, in any way compatible. You'll notice that this card has a fan. Most newer, high performance cards have fans. Even though this is a relatively low end card, it uses a fan to help keep the operating temperatures down. During normal computer use (surfing the web, working on documents...), the video processor isn't run very hard and wouldn't need a fan. For those who play video games with 3D graphics, the demand is much higher and the fan is required to prevent the card's GPU (Graphics Processor Unit) from overheating. For those who want a silent computer, there are silent cards that have HUGE heatsinks that can dissipate significant heat. These generally rely on convection or air flow through the case to help dissipate heat.

Although this doesn't apply to graphics cards, PCI-Express has been mentioned. The PCI-E connector above is a 16x interface. For applications where the data transfer rate doesn't need to be as fast as it does for graphics cards, 1x, 2x, 4x and 8x interfaces are used. The following is a 1x card. It's used for a parallel printer interface. I know many of you are asking why I'd still be using such an old printer. Well, it's because it's one of the best printer's I've ever owned. It's an old HP Laserjet 4+. It's not disposable like newer printers. With minor maintenance (spare parts are readily available), the printer still works like new. The 1x, 2x... tells you how many data 'lanes' the interface has. The more lanes, the faster the maximum data transfer.

As a Side Note...
'Drivers' haven't been covered yet but I thought this should be mentioned here. Drivers are software that tells two pieces of equipment how to communicate. All drivers are not created equal. Generally, the latest drivers are the best. The drivers delivered with the hardware are rarely the latest version. For example, the card above which was purchased in March of 2010, had drivers produced in 2007. Testing (benchmarking) showed dismal performance from this card. I had two other computers with integrated graphics adapters that outperformed this card. After updating the drivers from the manufacturer's web site, this card easily outperformed the integrated graphics adapters (as it should have).

On many of the graphics cards with heatsinks, the heatsinks are held in place by (weak) spring clips. These can be seen in the photo below.

If you bump the heatsink so that it is separated from the GPU, the GPU could fail. If the heatsink extends beyond the edge of the board, this is very easy to do and you may not even know that you did it. There is a layer of thermally conductive material (like you will see on the upcoming More on CPUs page). When the heatsink and the GPU are separated, the thermally conductive material isn't likely to remain perfectly distributed and is VERY unlikely to be able to efficiently transfer heat from the GPU to the heatsink. If you think you may have separated the sink from the GPU, download a program like PC Wizard that will allow you to monitor the temperature of the GPU. If it goes above ~60C at idle, you may have a problem. It's true that some high end GPUs will operate that hot if the fan is set low to minimize noise but most low to midrange graphics cards won't run that hot at idle.

VIVO:
VIVO stands for Video In Video Out. Graphics cards with VIVO can produce video to play on a standard TV and can accept a video signal to act as a video recorder (when the proper software is installed). VIVO cards often use a mini-DIN connector similar to that shown on the rear of the card at the top of the page. The audio input and output signals are passed through the sound card of the computer. VIVO cards typically have no tuner. They can generally only process composite video or s-video signals. If you want a card with a tuner, you need a video capture card or an all-in-one card.

In the following image, you can see the VIVO interconnect cable. It has two video input cables and two video output cables. Each input and output has two different connectors. The smaller connector is for 'composite' video. The larger connector is for S-video.

I mentioned before that you'll have to use the sound card inputs/outputs on your sound card to get the audio portion of any video you're passing through the computer. Many times, you have to use RCA type connectors. Since the computer has mini-phone (1/8" phone) connectors, you'll need an adapter cable. Below you see two different styles. One would require an additional patch cable. The other (if it's long enough), could connect directly to a camcorder or VCR. Both are generally available at Radio Shack.

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