Can two GPUs be linked via PCIe without a direct connection like NVlink?
Can two GPUs be linked via PCIe without a direct connection like NVlink?
Mother board: ROG STRIX Z790-E GAMING WIFI
Video Cards: NVIDIA GeForce RTX 4070
Hi,
I'm attempting to run a program that leverages multiple GPUs for better performance. When I try it, the system reports that my GPUs aren't paired. The video cards don't support NVLink or any physical bridge.
I wondered if it's feasible to connect the PCIe slots where the cards are installed—though it would be slower than a direct connection.
Could you advise?
Thanks!
A straightforward response is yes. You don't require an SLI bridge or NVLink for many non-gaming activities.
But they must share the same PCIe bus, and Nvidia especially needs eight connections for various functions. The second PCIe slot on that motherboard connects to the chipset at four connections, not the CPU.
Intel 14th, 13th, and 12th Gen processors
1 x PCIe 5.0 x16 slot
Intel Z790 Chipset
2 x PCIe 4.0 x16 slots (supports x4 mode)
You'd need to replace boards with ones that support eight connections per slot.
A better option is to purchase a single larger GPU and sell the older 4070 before the 50 series release.
Thank you for your clarification. Your board appears to have three PCIEX16 slots—PCIEX16(G5), PCIEX16(G4)_1, and PCIEX16(G4)_2. Does that affect anything? I attempted to upload a schematic image, but it didn’t work. A PDF of the manual is available if you need it. Thank you again for your help; I’ve been working on this for two days now.
Intel<sup>®</sup> 14th, 13th & 12th Gen Processors
1 x PCIe 5.0 x16 slot
Intel<sup>®</sup> Z790 Chipset
2 x PCIe 4.0 x16 slots (supports x4 mode)
ROG STRIX Z790-E Gaming WiFi | Motherboards | ROG United States
This ROG Strix Z790-E Gaming WiFi model boosts performance through its strong 18-stage power system, high-speed DDR5 RAM, and advanced PCIe 5.0 connectivity. It includes five M.2 SSD slots equipped with heatsinks, USB 3.2 Gen 2x2, WiFi 6E, AI Overclocking, AI Cooling II, AI Networking, and two-way AI features.
rog.asus.com
X16 is merely a design choice.
I reviewed the board details before responding. The second and third PCIe slots aren't meant for graphics cards. As Kanewolf noted, even with shared PCIe buses, your software may not function properly. SLI/NVlink was designed to link memory buffers directly, ensuring identical data across cards, which means total VRAM capacity equals that of a single card. Having multiple GPUs for tasks like rendering doesn't depend on a specific connection—real-time rendering usually needs true SLI. Motherboards with dual 8x slots don't automatically support SLI; it must be explicitly enabled and licensed by Nvidia. If you specify the application, a clearer solution might emerge.