Intermittent startup freeze due to Intel AHCI driver

Hi,

- The freeze is intermittent and occurs only during Win 7 startup, never afterwards (after 3 weeks of using the machine).
- The problem occurs only when adding the second drive, which is Seagate HD (not SSD). Never occurs with the primary drive only, which is Samsung NVM NVMe PCIe.

- It is definitely related to Intel AHCI driver because it does not occur when using Windows stock AHCI SATA driver.
- ASUS web site for the mobo provides two versions: 14.6.0.1029 and 14.8.0.1042. The problem occurs with both.
- I tried installing 15.2.2.1030 downloaded directly from the Intel website. Got an installation error towards the end related to RST; the driver installed successfully. Got apparently the same freeze during next reboot.
- Tried installing the driver only and driver+RST together. Does not seem to matter.
- Bios flashed to the latest version.
- LPM is disabled.
- Ran both check disk and Seagate tools on the HD. No bad sectors or any errors found.

Things I have not tried yet:
- Flashing HD firmware - can it resolve the freeze or it can only improve the performance?
- Another HD - need to get my hands on. Trying different drives can affect bios and os settings, making it somewhat time consuming. Apparently I have to do it.
- Another mobo.

Would appreciate any advice!

No replies may mean several things:
- I did not post it in the right forum
- I did not provide some important information
- My todo list (things I have not tried yet) covers all actions folk can think about.

Which one is correct?
Thanks again,