Mac Pro 5,1 does not recognize any of the 4 Sata ports on the logic board

The "usual suspect" is that the drive connector did not mate properly with the backplane connectors. The drives can physically be inserted far enough to get the door in place -- without actually making contact with the connector. There are many different ways this can go wrong.

Lay the unit on its side, and shine a bright light inside while you insert the drives to understand exactly what must happen to get each drive 'bottomed' in its bay.

Another option is the SATA Cable connection for the backplane is not connected to the Logic Board (or fully connected). If this Mac Pro had a hardware RAID card installed and removed, then it is possible the backplane was not reconnected to the Logic Board properly. I'm not sure if this is a possibility for the 5,1 model, or just the older models. Something to consider since it is highly unusual for all four internal bays to be non-functional.

Also, make sure to try with only a single internal drive connected just in case one of the other drives is interfering.

Manage to resolve the issue. Apparently it’s the logic board sata connector. I took the hdd n connected it to the cdrom sata cable n it works fine. Since, i hv no use for the cdrom i can put 2xhdd which i guess is better than zero.

Here is wat i did, i too had the same issue with all 4 sata port not functioning. The system wld not go into recovery mode command+r or any other command 4dat matter. I remove the raid card, remove all hdd connected to the sata on the logic board. I also remove the cdrom n connected 1 hdd to the cdrom sata cable n holy mother of God the freaking thing worked. I restore my previous image frm xternal drive. Once completed i remove the hdd n connected it back to the sata n the logic board n o’my Jesus all back to life. I initially tot the logic/b sata was a gonna but after days of r&d its bck to normal n i left the raid card out since I don’t use it, now all 4 sata slot are still in working order no thanks to apple. Hope dis work around helps u too.

Having the bay SATA connectors not usable in this model Mac Pro is EXTREMELY unusual.

<< It boosts to a white screen with a question mark inside a folder. >>

There are TWO possible issues with the question mark screen.

the usual issue is that the drive is not seen or is damaged.

the second, far less likely (but possible) issue is that the drive last-recorded as the Boot drive is not correct for some reason. Shuffling the drives around is one reason.

An experiment to try is to Hold the Option key at startup, using a USB keyboard connected to a port directly on the chassis, not on a display or other Hub that comes up to late. The Mac then discovers (by brute force) what drives are connected that might be bootable. It takes several minutes to complete the scan.

I had the same issue n I shined a light into the bay whilst inserting the drive n a full connection is made but i still get the same issue. It boosts to a white screen with a question mark inside a folder. I tested the hdd on another machine n there’s nothing wrong with it. Any others suggestions pls.

if you mean this RAID iPass cable, it was only used on the 2006 and 2007 models. For the 2008, 2009, and 2010-2012 models, fingers were added to the top PCIe slot for the extra conductors needed, and the RAID card was completely re-designed.