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Multiple Graphics Cards

Are Two Cards Really Worth the Cost?

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NVIDIA SLI

NVIDIA SLI Bridge

©NVIDIA
AMD Crossfire Logo

AMD Crossfire Logo

©AMD

Introduction

Similar to the promises of multiple core processors, having multiple graphics cards working cooperatively is supposed to provide improved 3D performance over a single graphics card. Both AMD and NVIDIA offer solutions for running two or more graphics in this manner. But are the solutions worth it for the consumer? This article looks at the requirements, benefits and whether consumers should really consider looking at such a solution.

 

Requirements

In order to use multiple graphics cards, there is underlying hardware that is required by both AMD and NVIDIA in order to run their graphic cards solutions. AMD's graphic solution is branded CrossFire while the NVIDIA solution is named SLI. For each of these solutions, a compatible motherboard with the necessary PCI-Express graphics slots is needed. Without one of these motherboards, having multiple cards is not an option.

Once the consumer has a compatible motherboard, there are also restrictions upon what graphics cards can be used together. Originally, NVIDIA required that two identical cards from the same manufacturer, model type and BIOS were needed to function in SLI. They have eased these requirements since then but the same graphics chip model is still required. As for ATI, a special CrossFire master graphics board is required to connect to a second card. This card typically costs more than a non-master board. This card can be used with almost any previous generate ATI graphics board, but performance improvements will vary depending upon the second or slave board.

Benefits

There are two real benefits of being able to run multiple graphics cards. The primary reason is for increased performance primarily in games. By having two or more graphics cards sharing duties at rendering the 3D images, PC games can be run at higher frame rates, higher resolutions and with additional filters. This can dramatically improve the quality of the graphics within these games. Of course there are many graphics cards that can currently render a game just fine up to 1080p resolutions which is common of most displays. The real benefit is from the ability to either drive games up to the higher resolutions such as new 4K Displays that offer four times the resolution or spanning a display across multiple monitors.

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

Disadvantages

The big disadvantage to running multiple graphics cards is the cost. With the top of the line graphics cards already pushing $500 or more, its very tough for consumers to be able to afford a second one. While both ATI and NVIDIA offer lower priced cards with the dual card capability, it is often better for the consumer to instead spend an equal amount of money on a single card with equal or sometimes better performance than two lower priced graphics cards.

The other problem is that not all games can benefit from the multiple graphics cards. This has improved greartly since the first multiple card setups were introduced but some graphics engines still don't handle it well. In fact, some games might actually show a slight decrease in performance over a single graphics card. In addition to this, the AMD CrossFire setups have show a problem with frame pacing that while might show improved framerates in benchmarks but result in delayed frames and some stuttering.

Today's graphics cards are very power hungry. Having two of them in the system can essentially double the amount of power required to run them in tandem. For instance, a single high end graphics card might require a 500 watt power supply to function properly. Having tow of those same cards might end up needing 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 computers wattage and the requirements before jumping into running multiple cards.

Finally, the actual performance benefits of having the multiple graphics cards can vary greatly depending upon 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 is typically recommended only in higher end systems.

Conclusions

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

Some people might benefit from the multiple graphics cards though. Users who do periodically upgrade their components rather than replacing their computer system may want to look into having the option for upgrading their graphics card with a second card. This can be an economic benefit to the user provided a similar graphics card is available and has dropped in price from the initial cards purchase.

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