In fact there are, at least, 2 factors to differentiate.I think axp90 x47 copper can handle the 9800x3D with AI overclock and if you turn on Turbo mode, even cooler, without decreasing TDP. Currently using it. Altough I hace my PC opened without cover. Maybe it is more noisy and not so cooler if you close it but still, I think it if you can handle noise if better perfomance for the cpu.
If you use it for rendering it might be different but otherwise…
CPU cooling : stand alone
In fact, AXP90X47 copper is performing in a similar way as the IS-47-XT, even if the AXP90-47 Cu is slightly better (but no a game changer). However, none of them is able to handle the R7 9800X3D at full load (IBT2.54 or Cinebench) even with -30 Curve optimiser/shaper. They are both reaching stock thermal throttle at 95°C of the CPU. Here is a table with the results I got while stressing the CPU alone, with variable TDP

CPU cooling : Gaming with GPU thezrmal interference
Even with the RTX 4080 Founder's Edition, there is some hot exhaust air from the GPU interfering with the cooling on the CPU. Fan duct (Noctua NA-FD1) + combined with quieter fan (Noctua 92 slim 2200rpm version) I have installed is helping on this specific point, more than I hoped.
Basically with Noctua Chromax 92 slim 2500rpm I was able to reach 95W TDP (CPU stand alone, max fan speed, very noisy) but only 75W TDP with gaming load with tolerable noise.
With the Noctua 92 slim 2200rpm + Fan Duct, I was able to reach, barely, 95W TDP, but while gaming, I'm able to reach 88W TDP with gaming load with tolerable noise.
Overall my second setup (Noctua 92 slim 2200rpm + Fan Duct) is the worst absolute performer but the best in real life..
I will also try using AMD PBO to fix the temperature limit, but leave power PPT by default.