Dell T30 RAID options

Looking to configure my T30 for RAID. Ideally, I would like to create one big array for all my hard drives.

I know that the T30 supports only a maximum of 6 hard drives. I didn't know this before I started, but I've modified the case and hardware to fit the following:

(8) 3.5" 8TB hard drives

Graphics card

850W PSU

128GB NVME M.2 hard drive (for OS)

I downgraded my BIOS to 1.0 in order to enable the NVME slot.

I also have a 4-port RAID controller and a 2-port RAID controller/PCI SATA expansion card.

Originally, I had 4 hard drives connected to the mother board via SATA, 4 hard drives connected to the 4-port RAID card. The system would not detect all of my hard drives, only 6.

I assumed that the NVME slot did not count as one of the hard drives because I tried removing the NVME, and the BIOS detected the same number of hard drives. Not sure if I was doing it correctly.

So, I removed 2 of the hard drives, thinking that I could run 6 hard drives + 1 NVME slot and everything will work. Now, I switched to my 2-port RAID card.

Now, the RAID card detects only 1 of the hard drives. File Explorer detects 4 hard drives. Now I've come to a conclusion that the NVME slot really does occupy one of the 6 hard drive spots.

So I removed another hard drive. This one from the 2-port RAID card. Now, my RAID card is only connected to one hard drive.

I pull up File Explorer, and now all the connected hard drives are detected. I have (5) 8TB hard drives and 1 NVME (running Server 2019).

At this moment, I'm a little down because part of my whole project was to be able to fit more hard drives into the tiny T30.

So, I go to Storage Pool setting in order to create my array. Only 4 of my hard drives are detected! 1 from the RAID card and 3 from the motherboard. I can see this because one says Adapter 1, and three say Adapter 0. 

After troubleshooting some more, I've come to realize that I won't be able to create this giant array anyway, because all the hard drives need to be connected to the same source. Either all connected to the motherboard, or all connected to the RAID card. At this point, if I can only have 4 hard drives combined into one array, it's defeated the whole purpose of my project. Any suggestions on what I can do? This is my first server so I thought the T30 would be a good entry level unit. Looking back, maybe I should have spent a little more on more features.

Someone suggested a different RAID card, maybe one with SAS and SATA port cable extensions? Though, I highly doubt that this will work, since there is a hard maximum of 6 hard drives on the T30.