Expanding Storage Option for mITX Plex Server

[jakeaw]

Recently I built a dedicated mITX computer for running Plex on, unfortunately I am running low on space. I  have a GTX 970 in my PCIe slot to help with trans-coding as HEVC streams hit my CPU hard.

 

Specs:

Lian Li Q25B

i7-4770K (LGA 1150)

ASUS Impact VI (Mini ITX)

GTX 970

OCZ SSD (Boot Drive)
3x 4TB Drives (RAID 5)
 

I am trying to to figure out what my best course of action is for expansion as all my SATA ports are in use.
What I have considered:

-Replacing the GPU with a SATA card (But this may affect playback)

-using the m.2 drive for boot (adds + 1 drive)

-using the m.2 for a 2 or 4 portSATA mPCIe sata expansion  (unsure about performance)

-new motherboard, but cannot seem to find one that fits my needs.

 

I am looking to try get up to 8 drives into the system, any suggestions or recommendations? I want to keep the CPU and Case the same.
 

[Firewrath9]

usb 3.0 to sata perhaps? the m.2 for boot 

the m.2 to sata also seems like a good idea.

Also how about pcie 16x to dual 8x then riser cables like 8x to 16x and 8x to dual 4x to sata?

[Alex Atkin UK]

The obvious solution would be to swap the HDDs for 8TB models, although that gets expensive especially as you should have backup drives too.  But remember having more drives has a long-term cost of electricity consumption too.

 

How many clients do you have and is it practical to replace those with ones that don't need transcoding?  GPU accelerated encoding typically has vastly inferior picture quality than the source so its not a great choice IMO.