MP 1,1-5,1 4,1 SATA failure on backplane?

[clorich]

Last night while copying files from a USB drive to the HD, all drives on the SATA backplane ports spontaneously disappeared. I tried all the slots, reset NVRAM, SMC with no success. Both of the SATA ports in the optical bays are working fine if I move the HDs up there. Right now running 10.13.6 from a 128 GB crucial SSD and a 1TB spinning drive on the second one. Since this was supposed to be a media server, not having the CD drive or the extra HD slots makes it a deal-breaker.

About two years ago, this computer suffered a power surge that fried both ethernet ports, but has otherwise been working fine. Any ideas or suggestions?

2009 single W3520, 8GB RAM (4x2), flashed to 5,1. Currently running High Sierra on the SSD and Yosemite on the main spinning drive. Has an old wifi card pulled from an iMac that works in Yosemite (but not HS).

 

[zedex]

It's a really weird problem and I can't quite isolate the origin of 'why' this also happened to my Mac Pro. No one has ever suggested a solution because the typical troubleshooting strategy does not conform to any 'known issues'. One thing that may be useful for you to know is that - regarding the SATA bays - the power part (15-pin) still works. Only the data part has died (7-pin). This means you can use power from SATA ports (bays 1-4) to 'spread' power draw for a GPU with high TPD..