I suspect there is a slight benefit for faster CPU.
Windows you should have at least 2 cores per GPU.
Running GPUs in the second x16 slot for desktop mobos will often be a problem too.
Even for my Ryzen5 3600 X570, the Gigabyte mobo had the 2nd GPU at PCIe x4 & about a 15% performance drop on a 2060 super.
Even with the M2 drive pulled, it was still a 4x slot (despite what their specs stated).
Switching to Xeon systems I have excess x16 & x8 slot capacity, but no GPUs for them.
Of course, being practical, lingering in the Top100 group is a sufficient goal.
Replacing less efficient GPUs with 3000 series would be a good strategy for the power-hungry Summer months in the US Southeast, even with a 19 SEER heat-pump in the basement (data dungeon).
I have two 3070.
giga is a Ryzen 5 3600 3.8GHz x16 PCIe4 x16 slot that boosts to near 5GHz
x9dr3 is a dual Xeon 2.6GHz E5-2650v2 PCIe3 x16 that boosts to 3.4GHz.
I can't say that one is better than the other... the Ryzen system seems to be a bit higher more often.
But taking a peek.... the xeon was higher.
I've not been motivated to upgrade to the faster 3.5GHz E5-2637v2, which would only be ~US$120 ebay.