Video cards (also known as 'graphics' cards) 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 games 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.
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. I've never seen a DVI, S-video or composite output integrated into a motherboard.
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.
Cooling:
In the image above, you should also notice that there is a relatively large 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. Some will even need fans to keep them cool.
Memory:
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 128-256MB of memory. In some of the better gaming cards, the memory is optimized for video.
Graphics Card Specifications
Memory: This tells you what type of memory (DDR, GDDR2, GDDR3...) and the quantity of on-board memory.
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 is for a relatively high-end card).
Auxiliary Power Connectors:
On some high-end graphics cards (particularly AGP 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.
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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