Mac3,1 2008 Power

I am not technical enough to know for sure what goes wrong.

At some point I am able to run the following at the same time
SSD as the macOS
Blu-ray drive
The above are parked at the 51/4 drive bay with SATA connections snaked from the board and power from the original drive bay.
Originally I have the power split cable connected to the SSD and the BR drive but it won't boot up so I bought another one with no split and everything works.

The 4 HDDs bay only has 1 4TB drive running.  At some point one of the 4TB turned bad and the OS couldn't use it.  I don't know if at any point all the drives were working.

But I am sure the SSD, BR and one internal 4TB and one 2TB USB drive were working happily together.

Then came the replacement of the 4TB.  When I plugged it into one of the 4 HDD bay the Mac won't even boot up.  Nothing.  Initially I thought it's the replacement drive but I know it can't be right.  It's supposed to be a new replacement.  Not that new new but new replacement like new refurbished.  So I swapped it with the USB.  And viola it works.  So I know something is wrong with the system but not the HDD per se.

It seems like I can't have all the drive running at the same time.  Mind you I don't ever have drive bay 3 and 4 mounted.

So I took the SSD down mounted it on the HD1 bay and the 2 HDD on bay 2 and 3.  So the 5 1/4 only has the BR drive.  Still won't boot up until I unplugged the BR power.  That's very odd.

I don't know if there's anything with the Y splitter cable even I only use on end of it.  So I am ordering another one without the split.  Or the BR drive drawing too much power?  I have no idea.  It seems like if I only put 1 HDD into the drive bay then it would boot up when the SSD and BR are plugged in and powered.

This is just a bit weird to me.