Two GPUs connected via PCIe lanes
Two GPUs connected via PCIe lanes
Hey there! I recently purchased a used RTX 3080 with 12GB of VRAM a few days back. As part of my upgrade plan, I was thinking about using two GPUs together. Since I need to replace my PSU, I wanted to know if running dual GPUs would be a good idea. My current setup includes an Intel i7-7700 CPU, ASUS Strix Z270F motherboard, 2x 16GB DDR4 RAM, and an RTX 1660 8GB GPU. The PSU is rated at 650W, but I’m considering upgrading to either 850W or 1,000W depending on what works best.
According to the motherboard manual, I have PCIe x16, x8, and x4 slots. My current GPU is in the x16 slot, and the manual mentions it can support a single GPU in x16 or dual GPUs in x8 + x8 (SLI). The question is whether moving the 1660 to the second PCIe slot and the new 3080 into the primary slot would affect its performance. I’m wondering if it would run better in x8 instead of x16, which could change things.
Running dual GPUs sounds appealing, especially since I mostly play older games but occasionally want to try newer titles. I also want to avoid overloading the 1660 and might save on power usage compared to keeping it idle as a backup. The PSU choice is still pending—should I go with 850W or 1,000W?
I’m planning to finalize my decision this week (before the GPU arrives on Thursday, Dec 18). I’ll be weighing the pros and cons, and would really appreciate any advice from the community. In the meantime, I’m just setting up a dual 1080p monitor and thinking about future upgrades like VR and more powerful hardware.
Hey there! It looks like the conversation has shifted. The 3080 handles everything on its own, so don’t waste time trying to limit it. Going for just 8 lanes won’t stop it from working as intended.
Yes, but those performance drops wouldn't make much difference since you'll face significant bottlenecks with the i7 7700. This doesn't really boost speed—it might even introduce a small delay for the few games you attempt on the 3080. Just use the 3080 and let the 1660 sit idle; it would appear unused if left alone. Multi-GPU setups are mainly useful for compute-heavy tasks like machine learning, 3D simulations, or rendering. If your main task is streaming games, a second card isn't necessary.
When a game demands over 12gb of VRAM, it often relies on system RAM for assets, causing slowdowns. I experienced this firsthand with my Alienware R11, which has limited PCIe slots running at x8, matching the specs of your Z270F. Upgrading from an 8gb GPU to a 16gb one led to significant performance improvements and eliminated stuttering in Rust. At least some YouTube reviewers have confirmed these benefits. If your titles don’t approach that memory threshold, you likely won’t notice much impact.
The screens should link to the 3080, while the encoding tasks run on the 1660. I prefer using 16 lanes on the main GPU instead of adding another card too close for airflow.
You might experience a drop in performance by about 5% when using PCIe 3.0 x8 for the 3080. Adding a secondary GPU with LSFG can boost performance. If you need high refresh rates but can't reach them with the 3080 by itself, consider it may not be sufficient. The 3080 should handle 1080p well already.
Thanks everyone for your guidance! This is exactly what I needed to understand or achieve. I’m planning a single GPU configuration and after some consideration, I’m leaning toward an 850W power supply. Reflecting on this, I also noticed I probably won’t rely much on frame generation anytime soon. I strongly dislike the industry’s focus on AI and the concept of fake frames. I really enjoy having games at near full resolution and think frame generation would only be beneficial in VR applications—especially since trucking doesn’t require high frame rates or ultra-low latency. I truly appreciate all your time and effort in assisting with builds and questions! Thank you! That’s accurate.
The CPU and motherboard are likely coming up next on my upgrade list for the coming years. The CPU is something I’ll need to evaluate more closely, as BeamNG.drive (with its soft body physics) is quite demanding, especially when traffic is active—each vehicle runs on a separate thread. That’s not a game I play often. I’m not overly concerned about VRAM usage. While I prioritize texture and shadow quality, I opted for the 12GB model instead of the 10GB because most games I’ll play in the next couple of years will be older titles needing more than 6-8GB of VRAM (and possibly 10-11GB if I upgrade to a 1440p monitor).
I hadn’t thought much about what my system could handle if it hit that limit, so thank you for pointing that out and sharing your experience.
Ah! I wasn’t very familiar with dual GPU configurations before. I didn’t realize I had the setup reversed! Great reminder about airflow—something I completely overlooked. Since I live in a tropical region, summer temperatures would definitely make things more challenging. I’m not sure yet, but I doubt I’ll face serious FPS drops in the next couple of years. I’m mainly a visual fidelity gamer; as long as my games run smoothly at 60 or 120 FPS consistently (with High/Ultra enabled) and I hit High/Ultra settings, I’m happy.
I currently use my GTX 1660 at 1080p with High/Ultra in 1440p, except for “Where Winds Meet,” which looks stunning on Low resolution. The main motivation for upgrading is future-proofing—enjoying VR more seriously, achieving stable 60/144 FPS in ATS (American Truck Sim), and being able to play newer titles at High 1080p or Medium 1440p for the next 5-8 years.