[Z600] Black screen (with a signal) after windows logo only when Nvidia 1060 drivers are installed

[i_have_a_proble]

Hello, I will just copy-paste my problem from another forum since they couldn't provide any help:

HP Z600 Workstation
MB: https://www.compeve.com/computer-ha...workstation-motherboard-460840-002-461439-001
CPU: Intel(R) Xeon(R) E5640 @2.67GHz
RAM: 16 GB
PSU: 650 W 85% (80PLUS Bronze)
BIOS (Legacy): Hewlett-Packard 786G4 v03.61, 05-Mar-18

I bought used ASUS GeForce 1060 DUAL 3GB from a trusted seller (today my friend tested the card and it indeed works). After trying to install the drivers for it using GeForce Experience I restarted the PC, and upon turning it on all you could've seen was BIOS info, then W10 logo, and after that, the screen went black - there was no "No Signal" message, it was just black (but the monitor was working) with no fans running (they were running prior to Windows loading screen).
I have tried installing many drivers (from safe mode), with and without DDU, updated BIOS, reinstalling windows, trying on a new SSD (with many w10 versions). I even tried removing CD/ROM and a few extra fans that came with Z600 Workstation because I thought there was not enough power for the GPU, it is always the same, no matter how I install the driver (I even tried running both cards in different slots) and so on and so on...

So, my question is - is there anything else I can try to make it work on my old computer? I searched the net prior the purchase to check whether the card was actually compatible with my old PC and I found a few examples where the poster had said that it was (there are instances on UserBenchmark with the 6GB version https://www.userbenchmark.com/System/HP-Z600-Workstation/875 ).