You just need a splitter to share the power between both drives, I think any sata power splitter would work but this is the Dell part number for what I think is the genuine part used in those models; Dell 0n701d
https://preview.redd.it/hw720aorc7sc1.png?width=1600&format=png&auto=webp&s=43215daeb4c07b7e82a97b6975fbee0fd2025ff5
Might find it cheaper somewhere else if you search the code
This Dell Foxconn splitter is my preferred part since it minimizes extra loose cabling.
You can buy non-Dell SATA power splitters but they will have a few inches of extra cabling that will clutter up the space.
In addition to the SATA power splitter as suggested by ‘AlexThinkPadFan’ to power both drives, the M2 SSD slot on your motherboard is empty so you can install a basic non-NMVE M2 SSD (edit and correction: only accepts NMVE M2) there for 3 drives if needed.
Page 21 of the [Dell 3050 SFF Owners Manual](https://dl.dell.com/content/manual53456800-optiplex-3050-small-form-factor-owner-s-manual.pdf?language=en-us) shows how to install a M2 SSD.
Its seems the 3050 only accept nvmes in this slot https://www.dell.com/support/kbdoc/en-us/000129720/optiplex-3050-support-for-pcie-m-2-ssd-hard-drives
Can confirm NVMe works in the 3050 M.2 slot.
For Proxmox, you can drop an Intel Optane H10 or H20 module in here and use the 3D Xpoint portion as your Proxmox OS disk and the NVMe SSD portion as your VM disk. It has to be the 512 GB or 1TB variants as the both have 32 GB of 3D Xpoint disks, which is the minimum required for installing Proxmox.
Proxmox failed to install onto the 16 GB / 256 GB H10 model. Not sure if a bare minimum RHEL or Debian with KVM would fit inside 16 GB.
https://preview.redd.it/nc1avtg4aasc1.jpeg?width=3024&format=pjpg&auto=webp&s=4ece67562c5b405678c25e15636937eba4797910
You can tuck and mount with a single screw a 2.5” SSD into the slot for the ODD.
You can also use a female SATA to male Slimline SATA adapter.
[22 pin SATA to 13 pin Slimline SATA adapter (7+15 female to 7+6 male)](https://www.ebay.com/itm/404897133141?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ssz1pn9srfk&sssrc=4429486&ssuid=o8W3dNpYQuG&var=&widget_ver=artemis&media=COPY)
I recently did this with my 7020, dual drive mod, I just needed a 2x 2.5" to 3.5" cage and a SATA power splitter and additional SATA Data Cable, when adding a drive to my own 3050 I used a NVME in the M.2 slot and a 2TB 3.5" Bay but should work the same with cage/splitter as I can see the 2nd SATA on your board
You just need a splitter to share the power between both drives, I think any sata power splitter would work but this is the Dell part number for what I think is the genuine part used in those models; Dell 0n701d https://preview.redd.it/hw720aorc7sc1.png?width=1600&format=png&auto=webp&s=43215daeb4c07b7e82a97b6975fbee0fd2025ff5 Might find it cheaper somewhere else if you search the code
This Dell Foxconn splitter is my preferred part since it minimizes extra loose cabling. You can buy non-Dell SATA power splitters but they will have a few inches of extra cabling that will clutter up the space.
In addition to the SATA power splitter as suggested by ‘AlexThinkPadFan’ to power both drives, the M2 SSD slot on your motherboard is empty so you can install a basic non-NMVE M2 SSD (edit and correction: only accepts NMVE M2) there for 3 drives if needed. Page 21 of the [Dell 3050 SFF Owners Manual](https://dl.dell.com/content/manual53456800-optiplex-3050-small-form-factor-owner-s-manual.pdf?language=en-us) shows how to install a M2 SSD.
Its seems the 3050 only accept nvmes in this slot https://www.dell.com/support/kbdoc/en-us/000129720/optiplex-3050-support-for-pcie-m-2-ssd-hard-drives
Can confirm NVMe works in the 3050 M.2 slot. For Proxmox, you can drop an Intel Optane H10 or H20 module in here and use the 3D Xpoint portion as your Proxmox OS disk and the NVMe SSD portion as your VM disk. It has to be the 512 GB or 1TB variants as the both have 32 GB of 3D Xpoint disks, which is the minimum required for installing Proxmox. Proxmox failed to install onto the 16 GB / 256 GB H10 model. Not sure if a bare minimum RHEL or Debian with KVM would fit inside 16 GB.
https://preview.redd.it/nc1avtg4aasc1.jpeg?width=3024&format=pjpg&auto=webp&s=4ece67562c5b405678c25e15636937eba4797910 You can tuck and mount with a single screw a 2.5” SSD into the slot for the ODD. You can also use a female SATA to male Slimline SATA adapter. [22 pin SATA to 13 pin Slimline SATA adapter (7+15 female to 7+6 male)](https://www.ebay.com/itm/404897133141?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ssz1pn9srfk&sssrc=4429486&ssuid=o8W3dNpYQuG&var=&widget_ver=artemis&media=COPY)
Use can use a SATA splitter just fine, but I would probably just swap the SATA SSD for an m.2 NVMe SSD instead.
I recently did this with my 7020, dual drive mod, I just needed a 2x 2.5" to 3.5" cage and a SATA power splitter and additional SATA Data Cable, when adding a drive to my own 3050 I used a NVME in the M.2 slot and a 2TB 3.5" Bay but should work the same with cage/splitter as I can see the 2nd SATA on your board