Computer wont start unless I switch an ATA cable

[SAINT4084]

I am running a custum built computer for an NVR camera survaillence system. It has four 1.5 and five 2.0 TB hard drives. It just recently crashed after running fine for six months. When I tried to boot it back up the error message "Reboot and select proper boot device or insert boot media" is displayed and I can't log into my Windows XP Proffessional OS (Service Pack 3). After several restarts, resets, and power off/on attempts I was able to boot it back up and get into windows by switching the ATA cable out with one from another hard drive. Each time it restarts successfully it is because I switched the ATA cable on the drive with my OS another's (leaving the other drive disconnected), but if I try to start it again without switching cables the same error is diplayed. Physically the the cable and the inside of the computer look emacculent. I can't make any sence of this intermittent boot error and really want to understand why it is doing this. Can anyone give me an explanation, theory, or solution?

Computer Specs
-Four 1.5 TB Hard Drives (Seagate)
-Five 2 TB Hard Drives (Seagate)
-Intel Core 2 Quad CPU 2.83 Giga Hertz
-4 GB PC16000 2000 MGH DDR 3 Ram (OCZ SLi Nvidea)
-ATI Radeon 512 Mb
-Asus P5Q3 Delux Mother Board
-1000W Power Supply

The drives are dynamically spanned.

 

[pjmelect]

You don’t give enough information to identify your problem but here are a couple of suggestions.
Why don’t you do what the error message says, “Reboot and select proper boot device” in the BIOS. By disconnecting a drive you may be changing the drive numbering so that the correct drive boots.
The drive that you disconnected may be faulty in a way that stops the boot drive from working.

 

[SAINT4084]

The computer boots up when one of the drives is disconnected and the cable has been switched at the OS drive. When I turn it off and try to start it with all my cables plugged in I still get the same error message, unless I unplug one and switch the main OS cable with another. Even if one of the drives is disconnected it still wont boot up unless I switch the main OS drive. If you can please tell me what other information you would like to know. Thank you for your feed back I really appreciate it.

 

[pjmelect]

Another idea (I am clutching at straws here) is that the power supply has gone faulty and can’t supply the load to all of your drives when they all try to start up at the same time. Some BIOS’s have the ability to delay the start up of individual drives because of this problem.

 

[SAINT4084]

I think guessed it right. I pulled power on one of the hard drives after noticing a faded blue LED on the power supplie's connection, it is a mobile power supply. After doing this the LED lit up brightly and windows booted normally. Thank you for your help.