Multiple Graphics Cards: Are They Worth The Hassle?

The Pros and Cons of Adding a Second GPU

Running Multiple Graphics Cards On a PC
©NVIDIA

Installing two or more graphics cards that work cooperatively provides improved video, 3D, and gaming performance over using a single graphics card. Both AMD and Nvidia offer solutions that run multiple graphics cards. Here are the requirements, benefits, and disadvantages of these solutions.

Requirements for Dual Graphics Cards

To use dual graphics cards, your computer needs AMD or Nvidia technology that links the cards together to produce a single output. The AMD graphics solution is called CrossFire and the Nvidia solution is named SLI (Scalable Link Interface). For each of these solutions, the computer must have a compatible motherboard and the motherboard must have the necessary PCI Express graphics slots.

To find out if the motherboard supports dual graphics cards, go to its official product page and check the specifications. Or, look for the Crossfire or SLI symbol on the box the motherboard came in.

Dual graphics cards also require a desktop case that is large enough to fit the extra hardware and a power supply that can run multiple cards. The cards must be linked using a bridge connector; which may be included with either the GPU or the motherboard. Finally, the SLI or Crossfire feature must be enabled in the GPU driver control panel.

Benefits

The primary benefit of running multiple graphics cards is increased video game performance. When two or more cards render the same 3D images, PC games run at higher frame rates and at higher resolutions with additional filters. This extra capacity improves the quality of the graphics in games. Most graphics cards render games up to 1080p resolution. With multiple graphics cards, games run at higher resolutions, such as on 4K displays that offer four times the resolution. In addition, multiple graphics cards can drive multiple monitors.

A benefit using an SLI or Crossfire-compatible motherboard is that a PC can be upgraded at a later time without replacing the graphics card. A second graphics card can be added later to boost performance without removing the existing graphics card. Manufacturers upgrade graphics cards about every 18 months and a compatible card may be difficult to find after two years.

Disadvantages

The primary disadvantage of running dual graphics cards is the cost. Top-of-the-line cards can cost $500 or more. While both ATI and Nvidia offer lower-priced cards with dual capability, you can spend the same amount of money for a single card with equal or better performance than two low-priced GPUs.

Another disadvantage is that not all games benefit from multiple graphics cards and some graphics engines do not handle two cards well. Some games may show a decrease in performance over a single graphics card setup. In some cases, stuttering occurs and makes the video game look choppy.

Graphics cards are power-hungry. Two graphics cards installed in a computer can 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; two of these cards may require 850 watts. Most consumer desktops aren't equipped with high wattage power supplies. Refer to the computer power supply wattage and requirements to determine if your system can run dual graphics cards.

The performance benefits of a dual-card environment vary 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 provides to the graphics cards. Dual graphics cards are typically recommended only in high-end systems.

Who Should Run Dual Graphics Cards?

If you don't play video games or use two monitors with your computer, you won't see an improvement in system performance by running dual graphics cards. The cost of the motherboard, the cards, and the other core hardware can be expensive.

However, if you run games across several displays or at extreme resolutions, dual graphics cards will improve your game speed and enjoyment.