Finally someone has done cpu tests with the 5090 and the results validate me not getting this GPU unless I also get a new CPU
Video below but here is the summary, and all results are relative to the 9800X3D that all 5090 reviews were based on:
9800X3D: 100% (baseline performance)
7800x3D: up to 80%
5800x3D: up to 70%
5600x: up to 50%
3600x: up to 40%
1600x up to 30%
So what this mean in practice?
If you have a 7800X3D, your 5090 will run up to 20% slower than if you had a 9800x3d.
If you have a 5800x3d your 5090 runs 30% slower
If you have a 5600x, your 5090 runs 50% slower
If you have a 3600x, your 5090 will run 60% slower
And finally if you have a 1600x, the 5090 runs 70% slower
based on these, I'd suggest anyone who wants a 5090 shouldn't bother unless they have or plan to have a minimum of a 7800X3D