Question Boot time and HDD"s


Sep 16, 2018

I am trying to improve my boot time, so I've done some tests to figure out what is causing it.
I5 8400, 2x 8GB 2133MHz, Asus B360 TUF Gaming Plus.
Boot/OS is a Samsung Evo 750 250 gb AHCI on Sata 0 port. Other HDD's: 480GB Kingston SSD, 4TB Samsung, 1TB Samsung (planar), 640GB WD (planar).
Latest BIOS, OS, drivers, etc.

Fast Boot makes no difference (from OS and BIOS).
Disable Full Screen Logo.
Post image set to 1 second.
Tried the lock numpad, wait for F1 ROM error, etc, did not speed it up.
Csm disabled.

System protection enabled on C:\.
Disabled indexing.
Disabled Cortana and Windows spyware.
GPT boot partition.
Program Performance - only one feature enabled.
Auto login.
No pagefile.
High Power mode.

Used to have the OS on a Kingston 480GB SSD (cloned to samsung) - 42 seconds total boot time.
Total boot time on the Samsung SSD is 38s.
I've timed each step of the boot process with different HDD connected.

With the Samsung SSD:
Post:10 Windows logo:12 Username:20 Desktop:24
With the Samsung SSD + Kingston SSD:
10 12 20 24
Samsung SSD + Kingston SSD + 4TB Samsung:
10 13 25 28
Samsung SSD + Kingston SSD + Samsung 1TB:
11 13 25 29
Samsung SSD + Kingston SSD + WD 640 GB:
18 20 27 31
Samsung SSD + Kingston SSD + 4TB Samsung + + Samsung 1TB:
11 14 28 31
With all HDD's:
11 18 34 38

The time until Post is about 10 seconds, with the annomaly of the 18s with just the WD HDD. This does not seem to manifest with all HDD's.
The time between post and the windwos logo is about 3 seconds, separately, but 7 with all.
Windwos logo to Username varies from 8 to 16 seconds with all HDD's.
Uername to Desktop is about 4 seconds.

Why are the HDD's causing the delay?