Double Your Frames With Multi-GPU Setups: SLI And CrossFire

Introduction

Gaming can be an expensive hobby, with the constant pressure to upgrade your rig to keep up with the latest games. One area where costs can quickly skyrocket is your graphics card. High-end GPUs often run $500+ for a single card. But what if I told you there was a way to double your graphics power without doubling the cost? Enter multi-GPU.

Multi-GPU setups allow you to link two or more GPUs together to share the graphics processing load. This can lead to significant performance gains in games, allowing you to maximize settings and frame rates. The two main technologies that enable multi-GPU are NVIDIA’s SLI and AMD’s CrossFire.

In this article, I’ll provide an in-depth look at multi-GPU technology, the benefits and drawbacks, how to set it up, some tips for optimization, and examine if it’s still worthwhile in 2022. Let’s dive in!

How SLI and CrossFire Work

SLI and CrossFire use the processing power of two or more identical GPUs linked together with a bridge connector. The bridge allows the GPUs to synchronize and share information rapidly.

There are a few ways the GPUs can split up the work:

• Alternate Frame Rendering (AFR): Each GPU renders full frames in an alternating sequence. GPU 1 renders frame 1, GPU 2 renders frame 2, and so on. This is the most common mode.

• Split Frame Rendering (SFR): Each GPU renders half of each frame or divides it further like a checkerboard pattern. The halves are then combined into a full frame. Reduces microstutter.

• Checkerboard Rendering: Similar to SFR but renders alternating blocks of pixels in a checkerboard pattern. Combines to make a full frame.

• SFR with Explicit Multi-GPU (SFR-EMG): Similar to SFR but uses Multi-GPU extensions to better handle frame pacing. Supported in some newer games.

The workloads can scale almost linearly, so two cards can deliver almost double the performance of one in ideal scenarios. However, scaling isn’t always perfect due to game engine limitations.

Benefits of a Multi-GPU Setup

Increased Performance

• The main appeal is substantially improved performance, especially at higher resolutions and graphics settings.

• In supported games, you can expect 70-100% improved frame rates versus a single card. This allows you to maximize settings while maintaining smooth gameplay.

Cost Effective Performance

• Multi-GPU setups provide much better performance per dollar compared to investing in a single higher-end card.

• For example, two mid-range $300 GPUs will outperform a single $600 flagship. The performance gains come at a significant discount over upgrading your GPU outright.

Future Proofing

• Multi-GPU provides some level of future proofing. When a game becomes too demanding for a single card, adding a second one can boost performance without a full upgrade.

• As newer GPUs get released, you can mix and match them with older ones and still get a performance improvement.

Drawbacks of Multi-GPU Setups

Driver Optimization

• Getting optimal multi-GPU performance requires driver-level profiling and optimization for each game. This doesn’t always happen consistently across every title.

• AMD and NVIDIA basically have to develop multi-GPU render paths on a per game basis, which doesn’t always occur, leading to subpar scaling.

Game Optimization

• Similarly, the game developers have to optimize for multi-GPU at the game engine level. Not all games do this well or even at all.

• Game optimization can have a huge impact and is likely the biggest factor influencing multi-GPU scaling. Poor support leads to low scaling.

Potential for Microstutter

• In some games, you may notice microstutter or jittery brief hitches in gameplay. This occurs when the GPUs aren’t syncing frames perfectly. Proper optimization minimizes this.

Increased Heat Output

• Packing two high powered GPUs into your system will generate more heat. Requires good airflow and likely increased fan speeds.

Higher Power Draw

• Dual GPUs also draw more total power, increasing your electricity costs and PSU requirements.

Limited Support

• While multi-GPU support is improving with DirectX 12 and Vulkan, explicit support isn’t widespread. Expect some games to only use one GPU.

Setting Up SLI or CrossFire

The process for setting up multi-GPU is straightforward. Here are the steps:

1. Matching GPUs

• SLI and CrossFire only work between identical GPU models from the same generation. You can’t mix and match different cards.

2. Motherboard

• You need a motherboard with at least two physical PCIe x16 slots to install the graphics cards. x8 slots may also work.

3. Bridge Connector

• Connect the two GPUs using either an SLI bridge (NVIDIA) or CrossFire bridge (AMD). Bridges are often included with higher end GPUs.

4. Power Supply

• Ensure your power supply provides adequate wattage for dual cards. NVIDIA recommends a 850W+ unit.

5. Enable Multi-GPU

• Finally, enable SLI or CrossFire in your driver software control panel. Set the rendering mode to your preference.

And that’s it! Your multi-GPU setup should now be ready to provide a performance boost.

Optimization and Configuration Tips

Here are some tips to help optimize and fine-tune your multi-GPU setup:

• Install matching GPUs from the same product family for best compatibility.

• Update to the newest stable drivers. AMD and NVIDIA often optimize multi-GPU performance in new driver releases.

• Favor games that clearly support multi-GPU render paths for smoothest performance scaling.

• Try different rendering modes like AFR, SFR, or checkerboard to find the optimal mode per game.

• If you notice microstutter or jittering, try enabling v-sync or capping frame rates below refresh rate to alleviate it.

• Set power management to “Prefer Maximum Performance” so cards don’t downclock.

• Ensure GPUs have adequate airflow and adjust fan curves to accommodate the extra heat.

• Monitor GPU usage with a tool like MSI Afterburner. Ideal scaling sees both GPUs reaching ~95%+ usage.

Is Multi-GPU Still Worth It In 2022?

Multi-GPU is in an uncertain place currently. Explicit multi-GPU support and optimization isn’t widespread in games. DX12 and Vulkan help by offering native multi-GPU features, but adoption remains limited.

Here are some closing thoughts on the current viability:

• For Enthusiasts Only: Multi-GPU only makes sense for enthusiasts pursuing maximum performance. It often requires tweaking and favors tech savvy users.

• Good for High Resolution Gaming: The performance boost is most impactful at higher resolutions like 4K. This is where multi-GPU shines brightest currently.

• Situational Value: Multi-GPU can be cost effective compared to upgrading, but only if your main games support it well. Check optimization before committing.

• Future Unclear: While multi-GPU support is improving, it’s unclear if explicit multi-GPU modes will ever become commonplace. The technology faces an uphill battle.

If you have specific high resolution gaming demands and your favorite titles support multi-GPU well, the performance potential makes it worthwhile in 2022. But for most mainstream situations, a single powerful GPU remains the smarter choice. Carefully weigh the pros and cons before pursuing this route.

Conclusion

While multi-GPU technologies like SLI and CrossFire can deliver substantial performance gains when well implemented, the inconsistent game and driver-level support limits the technology’s viability for most gamers. When it works, scaling can come close to a perfect linear improvement, but a lack of optimization just as often dulls the benefits.

Multi-GPU is a classic example of an exciting technological capability that has been held back by real-world implementation hurdles. Still, it remains a viable path for enthusiasts pursuing the cutting edge. And as explicit multi-GPU support gains traction, the future prospects could brighten. For now, double check game compatibility and scaling results before comitting. Carefully weighed, an SLI or CrossFire setup can still double your frames on the right rig.