MacPro3,1 can't split power from the 4-pin molex

I got one of those splitter but it won't work.  There are two 2 4-pin molex power plug in the drive bay of the MacPro3,1.  But you need 2 power adapters to convert the 4-pin molex to SATA power.  No luck with the Y splitter for that.  My boot drive, no ask me why, resides on that drive bay, using the power from the Y splitter when both are attached won't even boot up the MacPro3,1.  I mean using the Y splitter is totally fine as long as you only use one of the Y splitter but that defeats the purpose totally, doesn't it?  Got another adapter cable and now the BR drive and the SSD draws power separately and they work at the same time.  Hooray.