Computer does not detect hard drive on startup

I've suddenly been having this problem for the past week or so. Sometimes when I boot up my computer, my other internal hard drives (B and E) are not detected; only the C drive is. The disks don't appear in my computer, and the space doesn't appear to be available in disk partition (all of the files saved on those disks also cannot be accessed obviously).

Usually the problem fixes itself after a few reboots, but it becomes really inconvenient to reboot like 3-5 times every time I want to restart my computer. Does anyone have a possible solution? Any help is appreciated, thanks.

This is what my disk management looks like when everything is functional. When I get the error, the B and E drives simply do not show up anywhere (there is no "empty" space to partition either, as if the drives just don't exist)

Layback Bear said:

Things I would do if I had this computer to fix.

1. Swap the sata cables on the drives so Windows and Reserve were Drive (0)
Then make sure the computer boots.

2. Remove the drive letter from the Reserve Partition.

3. Partiton (B) should not be Active

Simple Example:

Alright I just did four reboots and seem to have no problem with the hard drives so hopefully the problem is fixed (or I just got lucky). Going to mark this as solved, thank you Layback Bear for your help.

Alright I hate that I have to revive this thread, but the problem just came up again. My B and E drives randomly disappeared while I was on steam (Steam froze then crashed because it was saved on drive B). This happened randomly after around an hour or two of normal use.

My hard drive model is a Seagate barracuda ST2000DM001 2TB if that helps.

This is what my disk management looks like after the two drives have disappeared.

Once again, any help would be appreciated! Thanks!

"B"... is that really allowed\recommended to use for a fixed drive ?