Unfortunately Time Spy is so old test that it is effectively not suitable for testing a system like this.
It is CPU limited on any system with a 5090 (or a 4090) and very much on the edge of it with a 5080.
AMD dual-CCD CPUs are problematic because Time Spy uses a very naive threading model "save one core for GPU driver, spawn helper threads for all other available cores" which means that on systems with more than around 8 cores, the extra overhead from the extra threads is greater than the benefit. More cores = more CPU usage. If you combine this with a fast enough GPU that is already hitting CPU limits with this test, you effectively get a scenario where more cores you have, worse your score is. So if you disable half the cores, you get better score.
Which is why we cannot recommend benchmarking this system with Time Spy.
9800X3D does not have the overhead issue as it only has 8 cores, and 5080 is (barely) not CPU limited, so the test isn't held back by the CPU limit issue on that config. 5090 on the same 9800X3D system will score slightly better, but it could do better with a faster CPU (or with serious CPU overclock) and is going to be held back by the CPU limitations. 7950X/X3D or 9950X/X3D all will have worse scores if you do not limit the CPU core count due to the overhead issue I mentioned if the GPU is fast enough to hit the CPU limitations.
Do not use Time Spy for modern high end GPUs or for systems with over 8 CPU cores - it is too old test released to a world where 4 cores was plenty and GTX 980 was a good GPU. Yes, we generally try to be foward-looking and Time Spy has survived surprisingly long (and Time Spy Extreme is still okay-ish due to the heavier GPU load, but it is getting close to hitting the same issue and >8 cores still adds CPU overhead) but Time Spy is effectively getting obsolete. Plenty of new tests exist that supersede it.
Instead, you should use Steel Nomad (no raytracing) or Speed Way (with raytracing) for modern high end GPUs and for testing CPUs released in the recent years, you should use CPU Profile.