This is a good comparison of the similarly priced 5800X vs 5800X3D.
It does not, however, actually address the title question: how much does the cache actually benefit?
You can only answer that question if you either lower the clocks/voltages to match on the 5800X (essentially under clock it), or lower the cache to match on the 5800X3D (which I don't know of any handy tool to accomplish this, but wouldn't call it impossible). You should expect them to perform identically except for cases where the cache actually benefits -- or detriments, although I can't think of any cases were it ~should~ do that, but this test as run would completely mask if that were the case, since you would just think it's because of the clocks difference.
Or you could change the title.
Here, we see many situations where the faster clocks allow the older chip to eek out the lead, and a few where the cache actually plays a big role, but it's not just the effect of the cache being evaluated because you have the clock mismatch.
Also - curious, why disable Resizable BAR?
The chart on Pg 6 where you break down the results so far -- nice to have the chart. It needs some coloring or something so you can tell which one was the winner, or include it in a bar graph or something. Just a chart of numbers is... hard to really interpret.
The CPU speed charts on Pg 8 are awesome, they do illustrate the clock delta that I did complain about allowing above -- but if you're going to allow it, and it's a valid point in a CPU vs CPU comparison (just not in a cache-only benefit analysis), may as well make it easier to interpret. They would be better if you could fix them so they have the same vertical range - would make it better to make a cross comparison, especially since they are sitting side by side.