Put simply, a video card is in charge of outputting a signal to your monitor. Depending on your task, this can be trivial, or very demanding.
This can be a very tricky step to visualize. When I talk to people about their video card needs, often they just know that they want a very clear picture and good graphics. At this point, it's important to try and separate what is handled by the monitor, what is handled by the video card, and what the relationship is between the two.
The video card is responsible for taking the information from your computer, and preparing it to be shown on your screen. This means it does all the necessary calculations for drawing images, sets the appropriate transparencies and colors, and a whole slew of other things. Once it has done all of the math, it gets ready to send the image to your screen by converting it to the signal that your monitor is expecting.
Traditionally, a video card outputs an analog signal called from a "VGA" port (which stands for Video Graphics Array). Recently, a new pure digital connection has been supplanting VGA as the new standard. This new type of connection is called "DVI", and has a much better signal quality. DVI is most typically found on Flat-screen LCD monitors. When purchasing a video card, it's a good idea to know whether or not you will need DVI connections. A $5 adapter will let you convert a DVI signal down to VGA, but you cannot go from VGA up to DVI without significant costs (as a bonus, most DVI capable video cards already come with this adapter). This means that if you plan on using a DVI based monitor, projector, or TV, it's wise to purchase a video card with a DVI port.
The clarity of the images you see are mostly derivative of the quality of your monitor.The video card mostly concerns itself with the preparation of these images for your display. The video card is actually like a motherboard of its own, with a processor, memory, and cooling system. When a computer is drawing images on your monitor, the Video Card does all the 2D and 3D work, freeing up your processor to work on other tasks.
Since the video card is like a miniature computer system, it's really complicated to describe its speed with a simple number! It has its own plethora of traits: clock speeds, RAM, cache, pixel pipelines, and a host of technical sounding features like "Vertex Shaders". Oh my! The complexity is only compounded by the rapid release of newer and faster cards.
I'm going to recommend the easy way out. Rather than comparing the gigahertz, the nanometers, and the megabits to compile some hypothetical model about which card outpaces which, let's just compare their real-world performance head to head. The guys at TomsHardware have a terrific tool that lets you do just that, which you can find here.
I can save you a bit of effort and sum it up pretty easily: The more expensive cards are going to give better performance. The most fundamental question is "which card is the best one for me?" All the charts in the world might not answer this simple question for you.
Here's the breakdown: If you're doing heavy 3D work, you'll need a very powerful video card. Here's a list of 3D based applications:
- Video Games
- CAD / CAM (when doing 3D design)
- Some Video Editing uses 3D transitions
- Graphic Design - Maya, Poser, 3DMax, etc
If you're not doing anything like this, you probably don't need an expensive video card!
Beyond processing power, there are a few other considerations to keep in mind when considering a video card. As mentioned above, you should keep in mind the type of connections on the card. If you plan on using a DVI Monitor, buy your video card with that in mind! Also, don't forget about the warranty given by the manufacturer. Most companies provide at least 1 year, and some even offer lifetime warranties! Finally, make sure it's compatible with your motherboard. Most modern motherboards have a PCI-Express Video Card slot, while older ones take an AGP video card. As long as your Video card is the same standard, you should be set.
There's one other thing to keep in mind about video cards: Windows Vista.
Windows Vista is the next version of Microsoft's operating system, and it's reasonable to expect many users to be upgrading to use it in a few years. If you might end up upgrading, then it's a good idea to be aware of the heightened system requirements. The video card requirements are the biggest leap from previous system requirements, and merit a bit of conversation.
Currently, for Windows Vista, you'll want a DirectX 9 compatible video card with at least 128mb of RAM. However, there are some features of Windows Vista which will only be available if you're using a DirectX 10 compatible video card. The catch, however, is that as I'm writing this article, no DirectX 10 video cards are available for retail yet.
What is Direct X?
DirectX is a collection of tools for easily handling tasks related to game programming on the Microsoft Windows operating system. It is most widely used in the development of computer games for Microsoft Windows.
Microsoft is currently working on a large update to the DirectX. DirectX 10, and later Direct3D 10, it will appear as part of Windows Vista. According to Microsoft, Direct3D 10 will be able to display graphics up to 8 times faster than DirectX 9.
Up till now, Windows has pretty much used Direct X as a tool for developing video games. Under the upcoming Windows Vista, DirectX will be used for many of the core functions of Windows. This means that even the average user who doesn't play video games will want to consider having a video card that can support Direct X.
So, in many cases for the average home user who plans on using Windows Vista, consider a really cheap video card now and then an upgrade when DirectX 10 video cards are available. If you're a high-performance power user, odds are you plan on frequently upgrading your video card regardless, so this is less of a concern to you.
Either way, a good solid DirectX 9 Video card will do great, but without a few of the visual effects available that you would have otherwise.