I do not know the precise power draw from that little connector but it could be upward over 50 watts.  Dell factory installed using power connector from motherboard with Dell part HG2F3 and connecting to the splitter with Dell part 247PN.  They both would be clipped down to the corner of the blue drive tray (hence you see 2 hooks near the edge).  Where to source your part will depend on your region and market.
Hi forum, I have just bought a used Optiplex 7040 sff and I would like to add a second 2.5" hard drive, the caddy has space on it but it doesn't seem to have another SATA power cable. There are three SATA data ports available on the motherboard but only two SATA power cables, one for the other hard drive and one for the optical drive. Am I missing something? How do I solve this? Thanks for your help!
Dell optiplex 7040 SFF second hard drive