The system is officially qualified by Dell for up to two high-performance, double-width graphics cards. Running three GPUs will likely require careful planning and potentially specific single-width models and dual CPUs.
Key Limitations and Considerations
- Official Support: Dell officially supports a maximum of two PCI Express x16 Gen 3 graphics cards. The total supported graphics power is up to 600W with a single CPU configuration (2 x 300W cards) or up to 320W with a dual CPU configuration (2 x 160W cards).
- Power Supply: The Dell Precision 7820 Tower typically comes with a single 950W power supply unit (PSU). Running three power-hungry GPUs may exceed the capacity or the available power connections of the standard PSU.
- Physical Space and PCIe Slots: The motherboard has a total of six PCIe Gen 3 slots (two x16 slots, and others wired as x8, x4, x1, and a legacy PCI slot). While there are enough slots, physical space is a major constraint. Most high-performance GPUs are double-width, meaning they occupy two physical slots.
- Configuration Requirements: Certain configurations, such as specific high-end 3D cards, are only qualified to be used in specific PCIe slots (e.g., slot 2 and slot 4 for the NVIDIA GeForce RTX 3080/3090).
Feasible Options
- Two High-End GPUs: This is the standard, fully supported configuration. You can install two double-width GPUs, like an NVIDIA Quadro RTX 6000 or AMD Radeon Pro WX 9100, and stay within the 600W power budget and physical constraints.
- Three (or More) Low-Power, Single-Width GPUs: It may be possible to install three or more single-width GPUs (e.g., NVIDIA Quadro P1000 or T1000) if you have the dual CPU configuration and can manage the power requirements and physical spacing.
- Modifications (Use at Your Own Risk): Some users in community forums have experimented with more than two GPUs in similar systems (like the T7920), but this often leads to technical difficulties, potential boot issues, and goes beyond official Dell support.
Conclusion
For a reliable and supported setup, the Dell Precision 7820 Tower is designed for a maximum of two GPUs. Attempting to add a third GPU, especially a high-power model, is not officially supported and will likely face power and compatibility issues.
