Multiple Graphics Cards

Are two video cards worth the cost?

Running Multiple Graphics Cards On a PC
©NVIDIA

Multiple graphics cards that work cooperatively provide improved video, 3D, and gaming performance over a single graphics card. Both AMD and Nvidia offer solutions for running two or more graphics cards, but deciding whether this solution is worth it to you requires looking at the requirements and benefits.

Requirements for Multiple Graphics Cards

To use multiple graphics cards, you need underlying hardware required by either AMD or Nvidia to run their graphics cards solutions. AMD's graphics solution is branded CrossFire, while the Nvidia solution is named SLI. There are ways to use the two different brands together. For each of these solutions, you need a compatible motherboard with the necessary PCI-Express graphics slots. Without one of these motherboards, using multiple cards is not an option.

Benefits

There are two real benefits of running multiple graphics cards. The primary reason is the increased performance in games. By having two or more graphics cards sharing duties at rendering the 3D images, PC games can run at higher frame rates and higher resolutions and with additional filters. This can dramatically improve the quality of the graphics in games. Of course, many current graphics cards can render a game just fine up to 1080p resolution. The real benefit is the ability to either drive games at higher resolutions such as on 4K displays that offer four times the resolution or to drive multiple monitors.

The other benefit is for people who want to upgrade at a later time without having to replace their graphics card. By purchasing a graphics card and a motherboard that is capable of running multiple cards, the user has the option of adding a second graphics card at a later time to boost performance without having to remove the existing graphics card. The only problem with this plan is that graphics card cycles are roughly every 18 months, which means that a compatible card may be difficult to find if you don't intend to purchase it within two years.

Disadvantages

The big disadvantage to running multiple graphics cards is the cost. With top-of-the-line graphics cards already reaching $500 or more, it's tough for many consumers to afford a second one. While both ATI and Nvidia offer lower-priced cards with the dual-card capability, it is often better to spend the same amount of money on a single card with equal or sometimes better performance than on two low-priced graphics cards.

Another problem is that not all games benefit from multiple graphics cards. This situation has improved greatly since the first multiple-card setups were introduced, but some graphics engines still do not handle multiple graphics cards well. In fact, some games might show a slight decrease in performance over a single graphics card. In some cases, stuttering occurs that makes the video look choppy.

Modern graphics cards are power hungry. Having two of them in a system can almost double the amount of power required to run them in tandem. For example, a single high-end graphics card might require a 500-watt power supply to function properly. Having two of these same cards might end up requiring around 850 watts. Most consumer desktops do not come equipped with such high wattage power supplies. As a result, it is important to be familiar with your computer's wattage and the requirements before jumping into running multiple cards. Also, running multiple video cards produces more heat and more noise.

The actual performance benefits of having multiple graphics cards vary greatly depending on the other components in the computer system. Even with two of the highest level graphics cards, a low-end processor can throttle the amount of data the system can provide to the graphics cards. As a result, dual graphics cards are typically recommended only in high-end systems.

Who Should Run Multiple Graphics Cards?

For the average consumer, running multiple graphics cards makes no sense. The overall costs of the motherboard and graphics cards, not to mention the other core hardware that is necessary to provide sufficient speed for the graphics, is overwhelming. However, this solution makes sense to those individuals who are willing to pay for a system that is capable of gaming across multiple displays or at extreme resolutions.

Other people who might benefit from the multiple graphics cards are users who periodically upgrade their components rather than replacing their computer system. They may want the option of upgrading their graphics card with a second card. This can be an economic benefit to the user, assuming a similar graphics card is available and has dropped in price from the original card's purchase price.

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