Home Server Support

[Context]

TL;DR:
My home-lab server stopped posting right after I added a PCIe NVMe adapter and an old GPU. I’ve already swapped in a second identical motherboard and tried many basic fixes, though it's likely I skipped some of the intermediate ones. I’m hunting for solid resources—or quick primers—so I can learn how to troubleshoot this myself.

Equipment: 

Mobo 1: Supermicro X9DRI-F | EAN: 0896051169885 | Socket Type: LGA 2011/Socket R | 5W

Mobo 2: Supermicro X9DRI-F | Ebay I bought it from doesn't confirm EAN (https://www.ebay.com/itm/333804770492)
CPU 1 & 2: Intel Xeon E5-2695 V2 | MPN: SR1BA | 2*115W = 230W

Memory: KTH-PL316LLQ/32G KINGSTON | PC3L-12800 | DDR3-1600 | 8*9W(worst case) = 72W

HDD: 8TB drives | 3*(~10W) = 30W

SSD: 2TB NVMe | 10W (worst case)
GPU: Nvidia GeForce GTX 1050 2GB | 75W
PSU: Seasonic FOCUS Plus 550 Platinum | ATX12V | (5+230+72+75+30+10) / 550 = 76.7% Load

 

Timeline:

1. 2019 – Built server for MS-CS for reinforcement of coursework with practical self-experience.
2. Graduated, started Chia farming; shucked 8 TB drives and used RAM-disk plotting (256 GB).
3. Same week – Installed the GPU and NVMe adapter card with 2TB SDD on card simultaneously → brief power-LED flash, then no POST (I think there was a single initial LED flash, but my memory might not be accurate due to subsequent panic)
4. Pulled new hardware, still dead. Attempted many other basic things like reset CMOS, etc...
5. Bought another X10DRi from a reputable eBay seller, moved core components over → identical no-POST behavior.

Request:
I'm fairly busy and while I would like to learn and be self-sufficient, I'm coming here for advice on a structured path to figure out how to recover my equipment if possible so I can re-use this hardware for some of my PhD research (going back to school again because apparently MS doesn't mean much when trying to get jobs which actually do new stuff [frustrated oversimplification])

[Not A Idiot]

update BIOS and drivers, maybe do a reinstall of your OS. My expertise is more in desktop PCs, but @Hinjima, @OddOod, and @strange13930 may be able to help you out.

[OddOod]

No POST after returning to original loadout? Probably a PSU issue

 

[Biohazard777]

@Context you've researched how much power you draw... 
But have you read the manual and hooked it up properly?

The manual says "24-pin and two 8-pin power connectors":
https://www.supermicro.com/manuals/motherboard/C606_602/MNL-1259.pdf

Looking at these power headers in the manual:

And taking a look at the picure of the mobo (found online):

Notice the locations of the "square holes" on JPWR1 and JPWR2:

So those are CPU power connectors, not PCIe...
 

And looking at your PSU:

https://seasonic.com/focus-plus-platinum/#specifications

You only have one such connector... so did you use some kind of an adapter or did you plug in just one?
( or I am reading the wrong PSU specificiation  )

[Context]

I'll have to get back you but, no adapter. I either plugged in one wrong, used a cord from something else, or didn't plug the other in. 

I did read the manual, doesn't mean I plugged in correctly. I think I did, but we all know what that's worth.

[OddOod]

46 minutes ago, Context said:

used a cord from something else

Thankfully, this is ~impossible.