Lolight

https://www.tomshardware.com/news/cyberpower-ups-smoke-reports-continue

As to finding a suitable motherboard and ensuring general system compatibility https://pcpartpicker.com/list/ could be real helpful. I'm not aware of similar to PSU tiered mobo lists.

Welcome! I'm not a fan of small cases no matter how aesthetically pleasing they are. Too many functional drawbacks IMO: limitations on storage expandability, airflow, upgradability and just generally harder to work with. I'd say the Node 804 is clearly superior on all those factors - accepts bigger mATX motherboards (easily found with 6-8 SATA ports), has plenty of airflow for HD's cooling, lots of room for expansion and easy to work on. You won't have a need for a HBA card either. As for a PSU (probably the most overlooked component) get the highest quality ATX model meeting your budget, from a reputable brand. Preferably of the tier A grade (single rail) in the lowest available at your local market wattage: https://cultists.network/140/psu-tier-list/

And how can one be sure that they weren't abused (mistreated, neglected, mishandled etc.)?

I'd suggest to check this video. Spaceinvader One has been tremendously helpful at everything Unraid.

If they're unable to raise prices in the inflationary environment then the production rates will get cut to the levels that achieve a new equilibrium. The companies are not going to continue to churn new product out if they can't meet their minimum profit margins. And the margins are slim throughout the industry.

Welcome! You might want to add a second cache drive - the first one to be used for downloads and the second one for app data. But then you'd have to change the processor to the 11th gen. Even though your selected motherboard features three M.2 slots, it has specific limitations on their usage. e.g. the first M.2 slot gets activated only with the 11th gen processors. the second M.2 slot if populated will disable one of SATA ports, but only if used by a SATA M.2 drive (make sure to purchase only NVMe M.2 drives). the third M.2 slot disables two SATA ports if populated by any of the m.2 drives, making it unusable for a NAS.

Memory prices have been very cyclical in the past. But I doubt we will see much of discounting for the rest. More likely the prices will continue to increase across the board.

Welcome! https://pcpartpicker.com/list/

I'm sorry but I don't quite understand your dilemma and the perceived need for HBA cards in the new system. I also don't think that there're any advantages left nowdays (reliability wise) to running the business oriented gear in a home environment. The modern consumer boards proved to be very reliable. By buying new SATA 16-18 TB drives and building a new system with a consumer market motherboard having at least 6 SATA ports, you could have plenty of the onboard SATA ports left and would still have lots of room for future expansion, if judged by your current amount of stored data.

The 8TB version of the WD Blue is CMR, the smaller capacities are SMR. Still, the price difference is not that great. WD Blues are inferior drives as compared to the rest. You might also look for the Seagate's Ironwolf Pro and Exos. In many markets the Exos, which is in certain aspects superior to the Ironwolf, sells at a discount to the latter therefore is being favored by many NAS users.

Stay away from WD Reds. Get WD Red Plus or Seagate Ironwolf/Exos

You don't need much RAM to get started. For a basic use case 16GB (2 x 8GB) is all you need. Non-ECC is fine.

That's why I've mentioned choosing motherboards with at least 6 or 8 SATA ports to allow for future expansion. Why to complicate the build by selecting small motherboards with few available SATA ports? A HBA card will also use non-trivial amount of electricity.

The motherboard's M.2 slots configuration needs to be checked via the mobo's manual. Thankfully you can find them published on the manufacturer's sites. So do some research before purchasing. Every motherboard is configured differently. e.g. my old Asus motherboard disables one of the SATA ports if one of the M.2 sockets is set to the SATA mode when populated by a SATA SSD. Yet, if the same M.2 socket is set to the PCIe mode and populated by a NVMe SSD then that restriction doesn't apply and no SATA ports get disabled. Is it going to be a direct connection between your NAS and PC? If not then the rest of the network would also need to support 10Gbps speeds, e.g. the router, switch... And I would advise to stay away from the newest and untested chips. All current gen processors are very efficient at idle. btw, you might also want to consider Jellyfin as an alternative to Plex.

The Node 804 is a very good case. I'd say select another mATX motherboard with at least 6, preferably 8 SATA ports that also features a couple of M.2 slots that are configured by the manufacturer not to disable any of the SATA ports when both M.2 slots are in use.

A good question. I had no idea that it was possible to run Unraid on Odroid-H2. Odroid-H3 looks to be very similar in every way while having more processing power. https://www.hardkernel.com/shop/odroid-h3-plus/

From Seagate Return Policy: "Products that are determined to be No Trouble Found (NTF) are not eligible for warranty service. Before returning your product, you may use the Seagate SeaTools diagnostic tool to determine the condition of your product and whether it is eligible to be returned under warranty. Seagate reserves the right to return NTF products back to their owner and may charge for associated shipping costs. If you send us through this RMA process any products that are not covered by justified warranty claims, we may retain these products."

6.12.0-beta4

Don't bother with ECC

His list contains a Node 304, that only accepts mini ITX boards. I'd agree on the advice to get a bigger case, e.g. a Node 804 running a mATX board - for better expandability, air flow and easier component access.

Could you please elaborate a little more on BlueIris and why it didn't suit your needs? I've tested BlueIris a few years back but haven't setup permanent camera's at that point. Now I'm thinking of installing a permanent system in the near future and would appreciated your thoughts on the monitoring software.

6.12.0-beta3

Sorry to hear about the problem. I'd suggest to repost this question into the "General Support" forum section.