Upgrading into the series 5000

Hi everyone, recently I've been planning to upgrade GPU, I have an old 3070, especially now with the new 5000 series from Nvidia. But I recently notice most of the new GPUs have PCI Express 5.0 and my current Motherboard only has 3.0 ports. I know both port are compatible, but what worries if it would cause bottleneck and if it would be better to upgrade my Motherboard first.