Precision T3600 2nd HDD not appearing

So yeah, searching through the forums, made some random changes little by little, a few errors (carelessness basically) encountered. Now my PC uses only 1 main HDD and I ditched the RAID controller card. Here's what I've managed to do as far as I remember:

So I've read some on the forums that going to the CTRL+R option at boot goes to RAID config utility, I did that, then someone managed to 'un-RAID' his HDDs from there by choosing the options 'Break Mirror', did that too, and somehow, one disk group appeared then there's some info added identical like on the pictures I've attached before. Now both HDDs say Online, I tried to reboot. Upon rebooting, there's still no sign of my other HDD on my system. So I went to disk management, and there I saw another drive, now assigned to F:, but it is a bit confusing because the drive is 100% identical to my main HDD, and that's not useful because of the same used space and free space, a little better but not much.

After having the 2nd HDD appear on my system, an accident (stupidity) happen where I chose my C: to be 'Active Partition', having read the warning though, I still agree with the prompt knowing that by doing this, C: would be my main drive so I can merge the 2 HDDs, but that was completely wrong and I messed up my system alot more.

Upon the next reboot, it now says that BOOTMGR is missing, and says to reboot. Now, another clumsy move on my part again as I went to the RAID config again, I never remember about anything what F2 options I chose there, but what happen is that, I got my 2nd HDD to be somewhat 'offline', I think an option to convert it as Non-Raid did that, so then I chose the option to 'Force Online' it but then it starts something that says 'Rebuilding' which is so slow that I rebooted over and over through the BIOS and the config untility with no luck of booting into my Windows.

So now, desperate of bringing my PC to boot back into life, I've come up with this application that makes a bootable USB drive, which then launches an app just like the Disk Management (app is called MiniTool Partition Wizard). I managed to boot the USB created from the application, but the system does not detect any HDDs now, I think I broken the 'RAID-bond' of the two HDDs, now both are undetected. So then I went to open the case, remove the card's cable that powers it, then I plug my 1 SATA cable directly to my HDDs at the bottom tray plus the power cable. Also some side notes, I noticed that my PC only has SATA 0 occupied with that 1 SATA cable, with the SATA 1 being blank, and that 1 SATA cable was from my DVD ROM, which I unplugged and making it useless for now.

So finally, I managed to plug my 1 SATA cable and power cable to my 1 HDDs, that's presumably, still has my Windows files to boot on. Upon doing that, I redid my steps on booting my PC through my bootable USB, and there, my HDD now appears on my system, which then I revert back my mistakes and now setting my Active Partition to System Reserved one. Now finally my PC now boots normally.

So after that journey of messing up a lot of settings, I can now boot my Windows back to normal. With the RAID card becoming useless and unpowered, though still attached to my PCI slot, and still slowing down my boot time. Not my biggest problem now of course. Now the remaining problem though is that my 2nd HDD now doesn't have any SATA cable to be connected to. Now the only viable option is I'm thinking of buying another SATA cable to be plugged in to my SATA 1 port to my 2nd HDD just to make use of it.

I wonder if I plug this 2nd HDD to my RAID controller again just to make use of it, though I'm now scared of messing up my system again so I will (patiently) wait for suggestions now.

AND that's what happen this day of messing my whole PC's HDD and bringing it back to life, though with some minor issues for now, 2nd HDD being useless because of lack of SATA cable.

Should I just buy a cable for my 2nd HDD and completely remove the RAID card? I will just patiently not tinker with my PC and wait for your suggestions. Thanks.

Your system was working exactly as designed. Your two disks were configured in a RAID 1 - a mirror - where the RAID controller makes sure the data is duplicated exactly on both drives. When one fails, then the system stays up and running, keeping services and data accessible while you obtain, replace, and rebuild the failed drive. If you view that as a waste of 500GB, then your data/services uptime is not crucial ... it is designed as a first-line-of-defense against critical business infrastructure downtime.

You obviously don't care about the protection and performance of the RAID card, so take it out and get a second SATA cable. Just know that that would not be an acceptable arrangement in a business environment where uptime of data and services is valued. This is not a regular PC, it is a workstation, designed to maximize performance and productivity in a business environment. (Sorry for calling it a server :))

Ohh right, thanks for explaining how RAID functions.

And yeah, I might as well just buy a 2nd SATA cable for my 2nd HDD as I'm just using this PC, traditionally, for mass storage at home. Thank you for your response.