gpu riser cable

I'm trying to build a multi-GPU unit for machine learning applications, and I'm new to all this. A lot of the design is based upon mining rigs, with a few differences. I suspect that bandwidth will be important for my application, and so I hope to use PCIe 16x connectors between each GPU and...

Here is my Motherboard: https://www.newegg.com/asus-rog-strix-z590-i-gaming-wifi/p/N82E16813119377 Here is my GPU: https://www.newegg.com/asus-geforce-rtx-3090-rog-strix-rtx3090-o24g-white/p/N82E16814126482 When I plugged my RTX3090 directly into the motherboard's PCI-E 4.0 GPU slot...