How Much Splitting Power is Excessive?

Currently, I am using a Great Wall E750 750W 80Plus Gold ATX 12V power supply in my system. I have only one SATA power cable available, which has three SATA connectors attached.

The first connector is connected to my fan control board located on the back of my motherboard. As for the other two connectors, I am using splitters to power my hard drives. To be more specific, I have connected two drives to one of the SATA connectors using splitter #1, and the other two drives are powered by the other SATA connector via splitter #2. Therefore, a total of five components are drawing power from this single SATA power cable. I want to confirm that I am not placing too much stress on this particular cable with my multiple devices.

However, there is a dilemma...

I misplaced all the cables during a previous relocation and cannot find them. I am hesitant to purchase a third-party cable that may not be compatible, as there are cautionary tales about using such cables. Although I have not encountered any issues so far, I am cautious about potentially causing unnecessary strain on my equipment.

Do you have any insights or suggestions for this situation?