My system currently has a SATA SSD and SAS 15000RPM HDD in it, the HDD goes through a PCIe RAID card and a cable that adapts the SATA power to a SAS connector. I want to replace that HDD with a 7200 RPM SATA (removing both the adapter cable and the RAID card entirely) and add an additional SSD to it.

Issue is I only have two SATA power ports to work with, and the manual says that the system supports two SATA storage drives and two optical drives, but the motherboard has ports for up to six SATA drives. I know I can use the SATA power from the optical drive for the third SSD, but I am going to need that in the future for an actual 5.25 optical drive.

So I wanted to know if anyone is aware if it's safe to split one of the SATA ports into two.

I noticed that technically it has a third SATA/SAS connector if I wanted to route the SSD through the RAID card: 

 

But I think that's more just a byproduct of making it possible to connect two SAS drives to the system and not intended to power three drives at once since the manual only states two. But since the system also is supposed to be able to handle up to two 15000 RPM drives, would a 7200 RPM HDD and two SATA SSDs consume much less power enough so I can safely split one of the SATA power cables into two for the SSDs without risking a fire or overloading anything?