I sort of solved problem. I physically disconnected the old drive. Boot time now 15 sec.
But now I've lost a 1 TB internal drive. I always had the SSD in front of the old drive in the boot order...

Of the 90 seconds of boot time, the first 9 seconds are black screen. The next 1:20 is a an ASUS logo with the option to go into BIOS. I disabled One Drive and ASUS Webstorage. I have AHCI turned...

I have an ASUS 6730 with Win 10 and I just installed an SSD as the boot drive. Boot time is very long 90 sec. I have the latest BIOS version. I tried disconnecting all external drives. I turned off...