WhiteAirLock

Step one is to get a the latest supported version of mac os. You should be able to do this with internet recovery
 
Then open core legacy patcher is what you what. Here is the download https://github.com/dortania/OpenCore-Legacy-Patcher

Make sure you're running Catalina first, and then you can use OCLP (OpenCore Legacy Patcher) to install macOS Ventura. I'd suggest waiting to do this until you get an SSD installed. Ventura is not going to run well on a mechanical drive. 

Truenas scale, proxmox, windows 10/server would all meet your needs
 
The HP ram is fine, and likely made with very simmilar dram chips to the name brand ones. I don't think its any lower quality
 

It's very decent to be honest. I personally would choose a different path, especially since team Red offers better options when it comes for the price of your CPU/MB combo but the whole thing about personal NAS boxes is about the personal need and budget.
 
For example I have a repurposed office PC that I bought for dirt cheap since it was a demo unit and I use it for data storage, local device backup and all my digitalized anime VHS/DVD/BD  and movie collection.
 
My setup:
Case > ASROCK DeskMini (includes 120w PSU)
CPU > Ryzen 5 5600G (I upgraded it from a Ryzen 3 2200G)
RAM > 2x 8gb Corsair modules (CMSX32GX4M4X4000C19)
m.2 > 250gb WD Red SN700
Adaptec ASR-71605 227440-R*  (a very great hardware raid card with a huge amount of connectors)
 
Storage (kinda jerry rigged into 3d printed enclosure since I used a hardware raid card here):
4x 10tb WD Red Plus (data storage/ raid 10)
4x Intenso Top Performance SSD 1tb** (raid 10 | anime/movie collection)
 
* great card. I really recommend it, especially since it has great features like....
• Support for RAID levels: 0, 1, 1E, 5, 6, 10, 50, 60
• HBA Mode and Simple Volume Mode for automatic deployment
• Supports up to 256 SAS or SATA devices using SAS expanders
• Supports remote firmware update
• 16 drive ports
 
** Since I also archive everything to a remote rented server, I don't care about the reliability of those SSD's. I just choose them because they were like 51$ for each one and I installed one into my mom's laptop and even though the SSD was tortured with all the Ubuntu updates and copying data from her DSLR to Laptop and then to her phone, it still is running fine since I installed it ( Dec 2019). The SSD's don't run all the time, they're automatically powered off when they're unmounted (I use a script for that) and there's no activity on them.

Both of those WX 3200 and 4100 sound actually really good. I would have to check the prices.
I already see a brand new WX 3200 in my area, which is sold for 160$ and the WX 4100 for 144$ used/refurbished

Radeon Pro WX 3200 would maybe have the best chance of matching with the custom bracket that P330 Tiny has?

Radeon Pro WX 2100, Radeon Pro WX 3100 are pretty good small GPUs. I have used a WX 3100 and it performs around the same as an RX 560. 
 
Edit: I forgot about the WX 3200 and WX 4100, those would work too and are a bit more powerful than the 3100

Thats good. The 3600x would not usually be worth the 40$ extra from the 3600 but if you got it for that price then thats great.

PCPartPicker Part List Type Item Price CPU AMD Ryzen 5 3600 3.6 GHz 6-Core Processor €174.90 @ Amazon Deutschland Motherboard ASRock B450M PRO4 Micro ATX AM4 Motherboard €69.00 @ Mindfactory Memory Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3200 CL16 Memory €55.90 @ Amazon Deutschland Case Cooler Master MasterBox Q300L MicroATX Mini Tower Case €43.10 @ Amazon Deutschland   Prices include shipping, taxes, rebates, and discounts     Total €342.90   Generated by PCPartPicker 2020-08-06 16:52 CEST+0200   This would be a good option. The thermaltake core's price is quite expensive in germany right now (about 30 euros more than usual). The case I have listed is also quite small and should work for you.

I'd say a Lenovo ThinkPad, a Dell Latitude, or an HP Elitebook. I personally favor the ThinkPad (I have two in front of me) for the keyboard and the TrackPoint but that's not everybody's cup of tea.

I agree with him..
ThinkPads have really good built quality and they have a very good keyboard.
You might be bordered by those WiFi cards which Lenovo puts into their Notebooks but it's not like those wifi/BT cards are soldered to the mainboard and don't have universal antenna connectors

Sorry, I've never actually done it before.  I was just tossing it out as a possible solution.  A youtube search might have a good tutorial.

Personally I think being in all the videos have started to take a toll on Linus... I've done so much worst to my/work equipment than what he was literally whining about...
 
Perhaps instead of building a 100K computer, take a real vacation?
 
 
Not related to above:

 
I forget which video (either iJustin tour or the mobile gimbal or some other video), but they literally have a editor that loves memes, my guess is he was the editor of the video.

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