My RTX 3090 has been crashing randomly while gaming, but my older RTX 2070 Super has been stable. Before I give up on troubleshooting the 3090, I'm wondering whether I can install both cards and choose which GPU each game or program uses. My system has a Ryzen 7 5700X, an ASUS ROG STRIX B450-F GAMING motherboard, 32 GB of RAM, an 850W Corsair RM850x power supply, and Windows 11 Pro. Would running both cards create driver, PCIe bandwidth, heat, or power issues?
4 Answers
Before relying on a dual-GPU setup, I’d focus on diagnosing the 3090. Test temperatures, power connectors, drivers, and stability under load, and try a clean driver installation. A second card can serve as a temporary fallback, but it won’t solve an underlying power, thermal, or hardware fault in the 3090.
The simplest approach is to leave only the GPU you want to use installed and move the monitor cable when switching. Both cards can coexist, but keeping a possibly faulty 3090 connected may make troubleshooting harder. If you do install both, put the 3090 in the top slot, connect displays as needed, and assign applications to their preferred GPU in Windows.
It is technically possible to install both cards and assign individual games to a specific GPU through Windows Graphics settings or the NVIDIA control panel. However, the second slot may not provide the same bandwidth as the primary slot, and installing both cards can add heat and driver-management complications. You would also need to make sure the power supply has enough headroom for the 3090, 2070 Super, and the rest of the system. An 850W RM850x is a good-quality unit, but the combined peak power can still be tight, especially with a 3090.
The two cards will not combine their performance for normal gaming, and you generally cannot have one game seamlessly use both. You can run different applications on different GPUs, but every program may need its own assignment, and some software may behave unpredictably. Check the motherboard manual for the exact lane configuration of the second slot, since using it can reduce the available PCIe lanes or bandwidth.
I’m mainly considering this as a backup plan so I can keep using the 3090 if I manage to repair it. Replacing it immediately isn’t really in my budget.