Aurora R13, blinking 4 amber/2 white, CPU power cable connection issue

Since that is a new power supply from Dell, the CPU power connection issue is likely with the motherboard.  Contact eBay seller for a refund/replacement.

On your old motherboard, did you replace the coin cell battery and clear CMOS by jumper?

Not specifically related to the CPU power cable issue, but I think you are going to need to boot from a Windows bootable USB and reinstall Windows because the product key on your new motherboard will not match the software product key on your boot drive.

@Chino de Oro​ Hmmm did not replace battery;  did do the "hold down power button for 30 sec with machine unplugged" routine to clear CMOS, but did not do the jumper thing.

Did you put the cables in the correct sockets?

The R13 uses one of those famous "12 Volt only" PSU's, divided over 3 x12 volt rails.

The 2 x 4 PIN white connectors, were they all wired up fully on the original 750 Watt PSU? I know Dell does not always fully wire them up on all models, and it can vary between the same models for some reason.

Check 11, 24 and 25 and see if the wiring is identical for those 3 connectors on both power supplies: Picture

I could have sworn there was somebody who posted they had extra pins on connector 11 when they did a PSU swap.

Found the thread: R13 extra PINS

@Vanadiel​ wait what??? are you telling me those two identical ivory power connectors near the VRegs and CPU are maybe not identical?  I didn't actually tag them A and B before removing.  I don't wanna get my hopes up -- because it seems to me that they face opposite directions and the wires are twisted to their habitual position, so I should not have got confused and reversed them -- but I will check.  OMG that would be an embarrassing but wonderful resolution.

Or are you telling me that Dell may have got the pinouts wrong on those connectors and I may have to reconfigure them?  will follow your links and try to understand.... [reads]. OK I am not sure that other thread is relevant as I am not using the 1350w PSU but a 1000w unit.  No extra pins on 11.

There are hmmm 5 PSU connections on my board, just as in the diagram you shared.  If you lay the unit down on its side with the base towards you (graphics card and PSU are closest to you) then... there's one in the lower RH corner of the mobo (ivory with some kind of RF shield over it, 11).  There are two on the GPU (black).  And there are two ivory 4-pin connectors on the top edge of the board near the CPU, 25 and 24.

I will compare connectors between old and new psu and see if anything seems odd.

So do those groupings represent the 3 rails of the PSU?  1 rail for most of the mobo, 1 for the GPU, and 1 for the CPU?

@Vanadiel​ thanks!

but where connectors look identical (like the 2 on the GPU for example, or the 2 near the CPU on the mobo) and are pinned identical, can we assume they are identical and swapping them has no effect?

BTW, I checked and on the old PSU, both the 4 pin power connectors are wired alike, 2 brown wires and 2 black wires.

when I first read your response I thought for a moment you were suggesting that the apparently identical connectors might not be equivalent, like one might be wired differently and it could matter which goes in which socket.  this gave me a moment of hope, that swapping the CPU power connectors might have some effect.  but on reading it again after a good night's sleep (plus your followup) it doesn't sound so much like that.

@Vanadiel​  you set me on the right track!

not that the PSU pinouts are different, but you made me look really hard at the cables again -- including the shortie that goes through the case between the PSU cable and the CPU power.  and yes, I had one flaky connector -- must have not plugged it in all the way to "click" when assembling, then put the side cover on and buried it.  it looked fine but came apart a bit too easily when I tugged on it.  really jammed it together this time as hard as I could, took a lot of force but I heard the click, that fixed it.  HOORAY got through boot!  HOORAY disks still intact!  HOORAY new mobo seems fine!  Dancing around my workbench here.

feeling a bit like an idiot of course, but still dancing around :-)

@ProfessorW00d​  Interestingly this was not a problem, so just for others who might worry... there was an auto reflash, then windows started to come up, and asked me to re-set my PIN (this required internet connection).  I reset my PIN (to the same one, of course) and then Windows came up correctly.  There was no complaint about missing or mismatched product keys.

So, if you transfer all components (boot drive especially?) to the new mobo it looks like Windows will realise it is still you.

@Tazling​    very interesting indeed.  Windows 11?

@ProfessorW00d yes, Windows 11 ... very relieved to find it did not disallow my license key.