I have recently taken hold of a HP Z840 Desktop with Win10 64 bit.
This was specced with the additional LSI controller for RAID, and it has 4 x 3TB HDD drives connected to that controller. The Windows OS appears to be housed on a separate smaller HDD as it can boot up with all 4 large drives removed.
By default, RAID isn't enabled and I'd like to get it set up. I've gone into the BIOS and set the controller to RAID rather than IDE or AHCI. Problem is whenever I try and boot the system with the 4 drives inserted, it simply sits at the black bios startup screen with the small square LSI controller window at the far right and hangs on the 'initializing' message. If I press CTRL-C to access the RAID menu, it goes a little farther but still hangs at the next screen - another black screen with an LSI Controller message in DOS-style text, and an 'initializing' prompt which sits there forever. I've left it for over 24hrs with no change.
If I unplug all 4 drives - it boots fine into the OS.
I've tried unplugging the 4, then going into the LSi config utility and setting BOOT Support to 'Enabled in BIOS' / 'Enabled in OS' / 'Disabled' and various pemutations, but nothing seems to work. Have also tried pressing CTRL-C to enter the LSi Config utility and then plugging in the drives just before that starts in an effort to leapfrog the issue, but I just get a random corruption error then.