ReadyNAS Pro rebooting and resyncing, with file copy hangups and other issues

I have installed the PSU.   Thanks to everyone who contributed to earlier PSU replacement threads!    They were helpful, and without them, I would not have attempted this repair.

ABOUT THOSE DRIVE POWER CONNECTIONS...

On the replacement PSU, there are four hard drive power connectors wired in pairs on two wire runs from the power supply.  The original Seasonic PSU has these as three wire runs, each with a single drive power connector.  Since each of the three drive power connectors in the ReadyNAS Pro powers two drives, it is surmised in earlier threads that it is not a good idea to run 4 drives from a single wire run from the power supply.   Instead, it is suggested that the diskette drive power wire is converted to another hard drive power connector, giving three wire runs from the power supply, each powering two drives like the original PSU.  

However, I cannot confirm if these three power supply wire runs all junction back to the same terminal points internally.   I think they probably do, and since each drive only consumes about 10-12 watts peak, that is only 40-50 watts on a single wire run if four drives are connected.  This would not seem to tax the fairly large gauge power wires.  

For now, I have not converted the diskette power wire to use on one of these three ReadyNAS hard drive connectors, instead running four drives from one PSU run, and two from the other.  I may make the conversion later.

HOWEVER, drive bay 4 does not work anymore!  I tried two of the previously known good drives in it, and they are reported as Dead.   The same drives are fine in other slots.  SO, I wonder if this is related to the PSU upgrade?   Did I break something accidentally?   Does this in fact demonstrate proof of overload on a single power line with 4x drives, as precautionarily suggested in an earlier PSU replacement thread.  If so, why is only bay 4 malfunctioning, and not one of the other 3 bays?  

Note that I have the top two drive power connectors in the ReadyNAS on the two plugs of a single PSU wire run.  I assume these are for drives 1-2 and 3-4, but I am not sure.  

THE REAL PROBLEM THAT WAS CAUSING REBOOT/RESYNC?

Have I finally hit upon what was causing the ReadyNAS to reboot and resync?   Was it because drive bay 4 was not working intermittently, and is now not working at all?   Maybe this PSU swap was not necessary, only just not using bay 4?   There was never any indication in the LOG files or SMART tables that drive 4 was having a problem.   It would just suddently reboot and resync.

Meanwhile, I successfully rebuilt an XRAID2 array using 3x2tb drives plus 2x4tb drives.   I am now doing a partial mirror copy test from the new NAS, and so far it has not gone into reboot/resync, which it would have already done before with the amount of data being moved.  For extra cooling during this copy, I am running a small box fan into the drive side of the unit with its door open.   Drive and CPU temps are reported in the 80s, which is low.   This is just a little insurance in case overheating was an issue before (I don't think it was.)

Assuming this first, partial batch mirror copy completes without failure, I will consider the unit useable as is.

I may modify the drive power connection wiring, and add a 4tb drive to bay four when the volume begins to run out of space.   Worth a try, and can't hurt anything?

Oh, almost forgot to mention, during the PSU swap, a small metal cooling fin fell off a chip on the bottom left corner of the motherboard.  I reattached that, and now wonder if the cooling fin was not doing its job with full efficiency before, leading to that chip overheating and malfunctioning?  This is yet another unknown in this DIY repair saga.

By the way, I think the new, forum-approved bandaids and bailing wire look rather spiffy on this old-boy NAS, which I want to keep chugging along, trouble free, for another few years.  I hope I don't soon post here that the darn thing is rebooting/resyncing again.   Fingers crossed!

Cheers,

Ear-Relevant