Ambious

PhD student in astrophysics; self described astro-engineer because I am not the typical astronomy student. My research interest is on instrument and telescope system design and observational methodology.

If only I could go back in time and give myself the same warning ?

There's more to a PSU than just the wattage.
Using any 10 year old PSU is a bad idea. Looking at the output, it's group regulated, meaning it's unsuitable for modern components. 

Probably best to replace it with something 80+ certified if you're planning on going with a 9900k and 2080

You can't have very simple and cheap ethernet port testers because you basically need to have an ethernet card connected to the port, and have that card send some data and receive data back from the switch or from the ethernet card on the other end.
 
You don't just have some voltage on the pins in the ethernet jack, ethernet uses pairs of wires and you need a tiny transformer on each pair of wires for isolation purposes, so the signal on wires is not continuous, it's pulses of electricity.
 
The cable testers you can buy cheaply online work in a totally different way... the end piece simply has some resistors or some transistors and leds (dumb side) and the main piece sends continuous DC voltage through each wire and on the other end if the voltage comes through the wire then you know that wire is connected properly in the ethernet cable.  These testers are just for testing if the wires are properly crimped in the ethernet jacks, they can't tell you if you have an ethernet card or a switch at the other end.
 
You could make something in the form of a usb stick with a microcontroller , a cheap ethernet controller IC and jack with magnetics built-in but the total BOM would cost you 5-10$ at least. 
 
A raspberri pi could be something cheap, you could write some code that would light up a led when the ethernet card receives an IP from a switch through dhcp or something, so when you plug the pi into the functional port
 

Such a device does exist, but it appears to be hard to find (as an example: https://www.amazon.com/Smartronix-Linkcheck-Ethernet-Tester/dp/B000RGI6R6) Other testers I've seen just test whether or not the cable is physically good or something, but not if any actual network is on it.
 
You could also find USB powered hubs/switches and power it with a battery bank.

Try making one yourself, just connect and LED to some of the wires of a known working Ethernet port and see if you get any blinks or anything.

Its rare to have hight adjustable desk. So you better start with getting chair into right height. That being when your legs are comfortable and you can keep them at 45* angle. Then get table so that arm rests are at the same height with table. Or bit lower. Your shoulders should be relaxed, not drooping too low or lifted too high.
 
Wrist rests and need for them is individual thing and also depends on keyboard. I don't use any with mouse, but like to have them with any keyboard I use. It makes better to keep wrist "active" and not have them drooped down when writing longer texts.
 
Monitor placing is also bit individual and depends on your monitor size and eyesight. Like I have 24'' main screen which is about 45cm from my face. And at the height where middle of screen is straigth in from of my eyes. If you look any guides on how to setup screen placement, they tell to have middle of screen so that you can look it at 45* angle while sitting with back straight.
 
E: Just remembered that I have pic from me sitting at the desk. I'm 183/4cm, desk's top is at 72cm, chairs seat at 47cm and armrests at 70cm. I can't adjust armrests smoothly and would like them at the same level with desk. But lower is better because notch higher is too high.
 

If you have a bit of talent with the soldering iron, you could make a sort of extension cable using a shielded cable (where you'd connect the shielding to one of the ground pins to protect the wires inside from catching noise from outside)
 
Some noise may also  be picked up from the USB ports, some case front panels connect the usb power ground to the audio ground so the switching noise from 5v of your power supply can be "injected" into the audio. Try and see if disconnecting the usb headers that go to your front panel make any different in the sound of your front panel connectors and if so .. other than physically separating the grounds on the tiny front panel circuit board, the only other solution would be to just NOT use the usb connectors.
 

Sorry to resurrect a really old thread, but I just realized I never updated it.
Lowering the desk did wonders, but what REALLY helped was getting a VESA arm, since I can now adjust the height and distance of the monitors on the fly and my "desk real-estate" as I put it is no longer an issue!
Just in case anyone else has this problem - now you know what helped for me :-)