techmattr

Depends on what you need. I really hate 16:9 aspect ratio on laptops so the XPS and Surface Laptop 3 are the only ones I considered. The HP and Lenovo have really bad touchpads so if you make use of the touchpad in Windows a lot then that may drive you nuts. The new XPS 2-in-1 has the maglev keyboard which is a love/hate keyboard. I love it. A lot of people hate it. The XPS 13 9300 didn't go with the maglev keyboard so it either isn't popular or its just needed in the 2-in-1 form factor. The XPS only has USB-C ports.
 
I mean you could write page upon page on how these are different but it just comes down to your preferences and requirements.

There was a 100+ page long thread on avsforums 5-6 years ago about media storage builds and about 10-20 of those pages we dove into the compatibility issues we were facing at the time with SAS2008 cards (and other HBAs) and Z77/Z87 boards. This brings back memories... The issue we were facing at the time dealt with running 3x SAS2008 HBAs on desktop boards and found that many of them didn't work even though they were electronically capable and it was a crapshoot finding a board that worked with 3 PCIe slots. We tried board with the exact same PCB but different model numbers and one would work with only 1 HBA and the other with 3 HBAs.... it's most likely a firmware issue as @leadeater suggested but ultimately it just makes sense to buy a server or workstation board that you know will run active PCIe slots 100% of the time.
 
As far as the drives not showing up on the expander.... how do you have it connected? It could be anything from user error to the PCIe slot not being active to bad Chinese eBay cables.

As @Electronics Wizardy said a NAS is a server. Both QNAP and Synology have built in synchronization with Amazon Cloud Drive and if they have Amazon Prime they can store unlimited photos at no extra cost. That includes the listed RAW files: https://www.amazon.com/gp/help/customer/display.html?nodeId=201649930
 
I have a Synology DS1815+ and really like it. I'm an amature photographer and sync all my photos to Amazon. I've run out of space on the DS1815+ though so I'm most likely going to upgrade to the RS2416+.
 
I also have a 24 Bay Supermicro / FreeNAS server but I'm guessing you're looking for prebuilt solutions.

I agree the product NextCloud Box doesn't seem optimal unless you're just using it for a few documents or something. I recently started using NextCloud as a DropBox replacement and I really like it so far. I'm running it in a VM with a separate NAS as the backend storage.

They are the only ones that offer containerized encrypted backup to Amazon Cloud Drive natively with their Hyper Backup. That may get stripped away at some point because it seems to violate ACD's terms of use for the APIs but so far it works great. 
 
As far as Synology vs QNAP. Synology for ease of use and low power configurations. If you're looking at more power Core i3 or above I'd probably go with QNAP.

I agree the product NextCloud Box doesn't seem optimal unless you're just using it for a few documents or something. I recently started using NextCloud as a DropBox replacement and I really like it so far. I'm running it in a VM with a separate NAS as the backend storage.

map it with ip, does that work?

nmap is open source, much more used, runs on linux and osx.

If it's a modern CPU, then there's no real point in downclocking/disabling cores or anything like that. Regardless it will sit at idle and consume minimal power. 
 
Also, the cost of buying a new PSU will likely far outweigh any savings from a higher efficiency. 

https://www.newegg.com/Product/Product.aspx?Item=N82E16811152273
 
Also, you can throw hot swap drive cages in any case with enough 5.25" slots. Like a  CSE-M35TQB or one of the Icy Dock ones.

Find a case with ample 5.25 bays and add a drive cage.  You'll have better options versus looking for one with an external cage.
 
I've had great luck with Icy Dock.
 
http://www.icydock.com/category.php?id=113