Optimizing GPU Performance: Exploring NVIDIA GTX 980 3-Way and 4-Way SLI

Table of Contents:

1. Introduction
2. The Performance Scaling of Multiple GPUs 2.1 Scaling from One to Two GPUs 2.2 Scaling from Two to Three GPUs 2.3 Scaling from Three to Four GPUs
3. Games That Take Advantage of Multiple GPUs 3.1 Crisis 3 3.2 Grid 2 3.3 Metro Last Light 3.4 Battlefield 4
4. Applications That Scale Well with Multi-GPUs 4.1 Unigen 4.2 3DMark
5. Power Consumption Considerations 5.1 Power Consumption of Four GTX 980s 5.2 The Benefits of a Back Plate for SLI Configurations
6. Conclusion

The Performance Scaling of Multiple GPUs

🎮 Introduction: When it comes to testing graphic cards, we at PC Perspective like to explore even the most unconventional ideas. That's why we decided to evaluate the performance scaling of four GTX 980 video cards in a four-way SLI configuration. While not recommended for personal gaming rigs due to limitations in performance scaling, we wanted to satisfy the curiosity of our readers. In our review on PCPart.com, we have examined the scaling from one to two to three and finally, to four GPUs using the GTX 980.

📈 Scaling from One to Two GPUs: As expected, the performance scaling from one card to two cards showed a significant improvement. In games like Crisis 3, we observed an 87% increase in performance. However, the scaling rate started diminishing as we added more GPUs.

📉 Scaling from Two to Three GPUs: Moving from two cards to three, the performance gain dropped to 39%. This indicated that the additional benefits of a third GPU were diminishing compared to the jump from one to two GPUs.

📉 Scaling from Three to Four GPUs: Surprisingly, the performance gain was even lower when we added a fourth GPU. Going from three to four cards only resulted in an additional 29% boost. In some games like Battlefield 4 and Metro Last Light, we even noticed lower average frame rates compared to using just three GPUs. It became evident that many games were not optimized to take advantage of more than two GPUs.

Games That Take Advantage of Multiple GPUs

🎮 Crisis 3: Crisis 3 proved to be the best example of a real-world title that scales well with multiple GPUs. With each additional GPU, we saw a considerable performance increase. However, the scaling rate reduced as we added more cards.

🎮 GRID 2: Unlike Crisis 3, Grid 2 showed limited scaling beyond two GPUs. The performance gain from adding a third or fourth GPU was minimal, making it less ideal for multi-GPU configurations.

🎮 Metro Last Light: Similar to Grid 2, Metro Last Light did not fully utilize the power of multiple GPUs. The minimal gains obtained from adding a fourth GPU made it clear that the scaling rates were not that high in this particular game.

🎮 Battlefield 4: Although Battlefield 4 is known for utilizing multiple GPUs, we discovered that going from three to four cards resulted in decreased performance. It became evident that adding more GPUs beyond two did not significantly enhance gameplay in this title.

Applications That Scale Well with Multi-GPUs

🖥️ Unigen: Unigen, an application designed to scale well with multi-GPUs, showed an impressive scaling rate of 20-30% with the addition of a fourth GPU. This demonstrated that certain applications could still benefit from a four-way configuration.

🖥️ 3DMark: 3DMark, another application that took advantage of multi-GPUs, showcased a scaling rate of approximately 10% with a fourth GPU. Though not as high as Unigen, it showed that there were still gains to be made beyond two GPUs in specific scenarios.

Power Consumption Considerations

⚡ Power Consumption of Four GTX 980s: Running four GTX 980s in a four-way SLI configuration led to a higher power consumption of up to 689 watts during our testing. Despite this increase, it was surprising to see that the power required to run four GTX 980s was relatively low compared to expectations. The GPUs individually had a TDP rating of 165 watts, but the configuration's power draw remained manageable.

⚙️ The Benefits of a Back Plate for SLI Configurations: The back plate featured on the reference video cards came with a removable section specifically designed for SLI configurations. In a three-way or four-way setup like the one we tested, removing this panel allowed for improved airflow and resulted in cooler and slightly quieter video cards. However, this feature might not be necessary for two-way SLI configurations unless spacing is limited.

Conclusion

In conclusion, our experiment with four GTX 980s in a four-way SLI configuration emphasized the diminishing returns of scaling beyond two GPUs in gaming scenarios. While titles like Crisis 3 and applications like Unigen showcased better scalability, most games only saw limited gains beyond two GPUs. Additionally, the power draw of four GTX 980s remained manageable, and the inclusion of a back plate proved beneficial for cooling in SLI setups. Ultimately, we recommend considering your specific use case before opting for a multi-GPU configuration.