Building an AUDIOPHILE friendly PC from scratch so what is a must to consider in 2020?

First thing-I realize there are computer audio web sites out there, but I would really like to know what the wise members of AGON have done or would do when looking at ensuring a QUIET PC can coexist when playing music in a mixed use office/listening room. Current Windows 7 desktop serves as my central ROON location. It directs audio sources( mostly streamed via TIDAL and RADIO PARADISE) to my system. I switch between an ALLO USbridge that runs USB to an MHDT Orchid DAC ("NOS tube days") or a CARY DMS-500 streamer/DAC ("DSD, Over-sample days"). Despite the problems it can add, I even on occasion use TIDAL's own PC based player. Regardless, the PC is always on doing something!
SO.... when seeking to maintain signal integrity AND limiting PC generated noise in my room ......are there some absolutes to consider when building from scratch? ( type of hard drive/SSD, power supply, pc case, cooling fan, network switch or specific style or brand to use of any?) KEEP IN MIND- I am not only looking to limit the corruption of any audio involving my PC but I also am really looking to LIMIT the NOISE the actual PC makes when I am trying to just listen to music while working !  Has anyone out there had any luck?
(***I realize Ipad, Iphone, can control everything via WiFi but my situation requires a desk top PC)  Thanks!
Also, with certain graphics cards (Such as Nvidia cards with MSI ZeroFrozr) the fans stop when the card’s temperature is below a certain point. You should be able to program your main cpu fans to do this too. If you also have an SSD, your desktop will not have any moving parts when it is cool.
At the very least, I would incorporate a program like Fidelizer with a Windows system.
A person to contact would be Sam Laufer of Laufer Teknik.
He makes The Memory Player, and Mini. He also offers software that aids in digital sound reproduction.
Lastly, you can try an Intel NUC. JRiver works well on it and gives you a lot of connectivity with streaming services.

I only use files from my pc....No cd anymore...I use stones to treated the electrical grid, the router, the phone cable line, the computer with success...Noise is everywhere in the electrical grid and not only in the computer...
I’m running roon with a PC in a closet, and streaming to a Raspberry Pi 4 with 4 Gigs of RAM, and Ubuntu. ~ $150, fanless.

A little more if you add a linear power supply.

The shopping list and parts detail are here, though when I wrote it I didn’t know I was about to switch to Roon:

To add to the previous comments, a general rule of thumb is that larger fans tend to be more quiet than smaller fans, since smaller fans have to turn faster to move a given amount of air. I would avoid 80 mm fans, and generally speaking 140 mm fans are preferable to 120 mm fans.

One of the best available CPU coolers, in terms of both cooling effectiveness and noise performance (even when used without the low noise adapter it is supplied with), is the following one made by Noctua, which uses a 140 mm fan:

However a relatively wide case is required to accommodate the height of this cooler.

I used that cooler in a computer I built last year, with the following case which includes two 140 mm fans in front and another 140 mm fan in the rear:

I built that computer for editing of 4K video material, among other things, so the CPU, graphics card, power supply, etc. that I chose are overkill for audio-related purposes by a large margin, but nevertheless it is very quiet.  I don't know, though, if its relatively large size would be suitable for your purposes.

Also, keep in mind that for tasks that are relatively unchallenging for a computer, such as processing of audio material, it may very well not be necessary to connect all of the fans that are provided in a given case.

Good luck. Regards,

-- Al
Or none at all. A modern (current) fanless SOC / Motherboard.

it may very well not be necessary to connect all of the fans that are provided in a given case.

Get a Sonore Rendu streamer and the cheapest retail SILENT computer that will run your music software. If you can make the streamer work on fibre optical network the better.

I have a cheap DELL my old company was about to throw out and lower end Rendu, the microrendu. I bet this system sounds the same as a optimized PC.

BTW- I know how to put together a PC from scratch but I do not bother because of the Rendu.
SSD hard drives. 

I actually use a fanless video card.  The Palit Geforce GTX 10050Ti.  I wanted my PC as silent as possible as well.  The Palit video card works great for all 2D stuff (web browser, video, youtube, Word, Excel, etc., etc.).  It works well for mild 3D gaming also.  However, if you are running some of the more aggressive 3D games, you absolutely need a fan or multiple fans on the video card.  This card just gets too hot on aggressive 3D gaming.

Teradak used to sell computer linear power supplies in separate cases on ebay, but it looks like they have stopped.  You still want some sort of fan that will circulate air within the computer case itself.
Depends on what other thing you are planning to do with the computer and what you want to spend. If you use USB to connect  to your dac consider something like a femto USB card they are expensive. For hard drives PCIe instead  of sata easier on the CPU. There are some fanless cases but if you use fans use large as you can get in the case. Get the best CPU with the most cores you can afford , most memory you can afford, won't tax the computer as much and will run cooler and quiter. 
Many great insights-Thank You!
The most often mentioned point both in research and here absolutely agrees on the importance of  choice of hard drive and its SSD by a MILE.. Of which- My builder says an M.2 drive is the best route within this area. If anyone else has experience with M.2 and any potential implications on audio- please let me know. (OS on one smaller drive-everything else on a much larger 1TB plus second drive)
As much as a Teradak linear power supply would seem to really make sense coming from our "audio first" point of view -it seems pricey- if even available at this time- for the little ROI it might provide -especially if Cary DMS- 500 is doing most of heavy lifting from Roon's direction.
Either way -All great points!
Any new SSD will have plenty of speed to stream audio. M.2 is damn convenient, but don’t bother overspending. If this is dedicated for audio get the biggest, slowest M.2 drive you can. 😀. The top of the line Samsung Evo Pro will be severe overkill for speed.  Better to vet a larger past gen model for the same price.
I see no reason why an M.2 drive for the OS and and a 1 TB SSD in either the M.2 format or the SATA format for everything else wouldn’t be fine choices, assuming a fairly recent motherboard is chosen which can accept M.2 drives.

For the computer I mentioned earlier that I built last year I chose the following well reviewed drives (in addition to a 4 TB HDD for additional storage), although the M.2 is a good deal larger than what you would need for just the OS:

I can’t say, though, how optimal such a computer would be from an audio standpoint when connected directly (i.e., via wires) to an audio system. When I play music from that computer, which is not one of my main sources (although it provides excellent results), and which is located in a different part of the house from my main audio system, it communicates via wifi with a Squeezebox Touch, which in turn is connected to my audio system via an optical S/PDIF cable.

If it would be of interest I can list the rest of the components I chose for this computer. It has worked smoothly and perfectly (and quietly!) from the very first time it was powered up, although as I indicated earlier it would be overkill for your purposes.

Good luck. Regards,
-- Al

M.2 drives are now cheaper than sata as well as faster.

You mentioned Audiophile computer which is why I suggested the Jcat femto USB card but it’s about $500 I wasn’t sure if you were putting it close to your USB dac.