Over the past few weeks I've been planning on a mod for my R710 which included adding another 2.5" drive but wanted to make a cable instead of splicing into the OEM cable. There were a few reasons for this.

1. The OEM optical drive cable has relatively thin gauge wire
2. The OEM cable has a SATA cable molded into it
3. The OEM cable only supports slim SATA connections (which would require an adapter)

So I set out to source some parts. Turns out TE Connectivity Micro Mate-N-Lock part #794617-4 connector and part #794610-1 socket pins are just the ticket to connect to the DVD/TBU_PWR port on the R710 motherboard.

I already had some 8 pin Micro Mate-N-Lock connectors laying around so I just snipped one of those connectors down... The above part number is for the appropriate 4 pin.

I also had a crimp style SATA cable from a modular PSU laying around. It was never used so the wires and connections are still in perfect condition.

I removed the 3.3V wire and crimped on the socket pins. I referenced the GP700 cable images found online to get the appropriate pinout. Going by the photos and how the OEM DVD cable is laid out, 5V positive and negative are at the top (closest to the tab) 12V positive and negative are on bottom.

Here was is completed cable

I'm not able to find much of a source on what the power draw of the Dell TBU is and I'm not sure what the capability of the DVD/TBU_PWR port is. For testing, I went with the "screw it" route... I used two 3.5" mechanical drives. Which the server seemed like it couldn't care less... No errors and nothing was even warm. The drives showed in the BIOS and hummed along happily for the few hours I left them during testing.

I'm going to be running a pair of SSDs so the power draw should be less than 3W per SSD which even if the SSD only runs the 5V rail (which it probably will) is still a bit less than the 5V combined rating on the mechanical drive's decals.

So hopefully this was informative to anyone that may want to make a cable for themselves.