Video Card Buyer's Guide Part I: Video cards 101

However, buying a new video card can be daunting. Like processors, video cards evolve rapidly and there's a dizzying amount of options to choose from, so the chances of spending too much money on a card not suited for your needs are high. In this 2-part series, we'll explain how video cards work, tell you what specs to look for, and shed light on some common buying misconceptions.

Interface
Before you buy a video card, you'll need to know what kind of card your motherboard supports. (Check your motherboard's documentation if you're not sure). There are three main types of slots to look for on your motherboard: Peripheral Component Interconnect, or PCI; Accelerated Graphics Port, or AGP; and PCI Express (PCIe). Of these, the PCI bus was the first interface developed and, unfortunately, it's also the most limited in terms of performance and options. Few manufacturers still make PCI video cards and the cards that are available are anything but cutting edge. After PCI came the AGP bus. While PCI was designed universally to work with most peripherals, this interface was designed specifically for video cards, providing up to an 8x performance boost over its predecessor. However, it too is dated, although there are still some AGP video cards in the market. Today's standard is PCI Express (PCIe), which supports higher bandwidths than both PCI and AGP. There are various types of PCI Express connectors (x1, x2, x4, x8, and x16), but the one most commonly used for video cards is x16. If you plan on installing more than one video card (more on how to do that later), you'll likely need a motherboard with two PCI Express x16 slots.

The GPU
At the heart of every graphics card lies the graphics processing unit (GPU). The GPU is responsible for processing graphical algorithms on your computer. In other words, it's responsible for any visualization effects displayed by your computer, from eliminating pixilation on your videos to rendering shadows and detailing in your favorite PC games. A GPU's horsepower is measured in megahertz and referred to as the clock speed. Some manufacturers sell overclocked video cards where the GPU has been tweaked to work as fast as it possibly can. To avoid burnout, most overclocked cards (and even many cards that aren't overclocked) rely on cooling solutions such as fans and heatsinks to keep them from overheating. Most users, however, don't need overclocked cards and can find more than enough processing power with what's available on the market today. There are currently two types of GPUs worth noting — the NVIDIA GeForce series and the ATI Radeon series.

Memory Types
The second most important thing to look for when buying a video card is the memory. The memory is in charge of storing, reading, and writing graphics data which, in turn, impacts the overall performance of your video card. It's important to pair your GPU with sufficient memory; otherwise, the GPU can be bottlenecked by the RAM's performance. The most common memory that you'll find in video cards, listed in order from slowest to fastest, are DDR, GDDR2, GDDR3, GDDR4, and GDDR5. Like the GPU, memory speed is also measured and referred to as memory clock. Memory clock speed ranges from 100MHz for the lowest-end DDR RAM to a theoretical 6GHz for the latest GDDR5 RAM. However, splurging on a video card with massive amounts of memory doesn't always guarantee jaw-to-the-floor graphics. The memory must be paired with a GPU that can take advantage of it, so don't buy a video card packed to the gills with memory unless it's accompanied by a powerful GPU.

Using two cards at once: CrossFire and SLI
When played at their maximum settings, many of today's PC games can be very demanding. To solve this dilemma, both ATI and NVIDIA offer competing dual-card technologies. ATI calls their technology CrossFire, whereas on NVIDIA's GeForce video cards you'll find the Scalable Link Interface (SLI). No matter which GPU maker you go with, the two cards you pair must be the same make and model. In addition, your motherboard must support a dual-card setup and offer enough expansion slots to fit two cards. Keep in mind that for the average computer user, this option can be both expensive and overkill as there are enough single-card solutions to keep most users happy.

How much should I spend?
Don't upgrade your graphics card just because new cards are available. It's best to check out multiple reviews and benchmarks (ExtremeTech, Anandtech, and Tom's Hardware are all good sources) before purchasing any new card. Often times, the latest cards offer little to no performance increase despite carrying higher price points. When shopping for a new card, also remember that the high- and low-end cards will offer the least value for your money. To make your dollar go far, look at mid-tier cards, which dust the low-end cards and in a few occasions have been known to tie or outperform their high-end counterparts.

So what cards are out there and what kind of deals can you expect to see? Next week we'll explain NVIDIA's and ATI's naming conventions as well as list some of the best deals we've seen on today's most sought-after cards.