How about this mobo: Gigabyte X570 Aorus Pro? Some mobo's don't work right away with the Ryzen 9 3950X, and some need a bios update. This one works, and is not too expensive either. Can't they just order a good mobo (abroad)?
I've checked a good number of reviews and tests and this configuration will be my purchase:
power supply: Corsair RM750x €135,05
CPU Cooler: be quiet! Dark Rock 4. €69,45
memory: CORSAIR Vengeance LPX - DDR4 - 64 GB: 2 x 32 GB - 288-PIN - 3200 MHz - CL16 - 1.35 V - zwart €265 (2 slots left, so can be extended)
case: Fractal Design Meshify C - Dark TG €99,50
CPU: AMD Ryzen 9 3950X 3.5GHz 16-Core Processor €761,05
storage: Samsung 970 EVO Plus 2TB. €336
Motherboard: Gigabyte X570 Aorus Pro €240,85
GPU: MSI GeForce GTX 1660 Ti Gaming X 6GB €315
Software: win 10 Pro licence €143
It's under €2400, and when I look at those workstations at Boxx, they are around that price at least, and have less 'in the box'. What's the difference between a workstation and a pc anyway?
And you are probably right that a high end GPU like (RTX 3070) is overkill. As it was still hard to get, I have changed to a lesser GPU, but still one that reviewed very well.
I hope you'll find what you need!