sh4z

What is the mainboard btw? (Gigabyte B550 AORUS ELITE AX V2 ATX AM4?) Check that your power switch cable for the case front panel etc are in the right pins on the mainboard, It could be as simple as putting a cable in the wrong spot. make sure the PSU is switched on at the back of the unit. Page 11 on the manual has the front panel pin out details. Check that all your power cables are plugged in correctly/securely. Unplug anything from the PC that isn't necessary, just to simplify testing (Extra peripherals, usb hubs, webcam etc) try with nothing plugged in and then move on to keyboard only.

@klemm what sort of temps you get with that case setup? the drives look pretty close together. do you control the fans manually ?

If it's legit I want one!

Fans are spinning and lights on means PSU is probably okay. Pull out all the ram and listen for beeps or monitor for any changes. I'd pull out the gpu with the ram out and try and monitor for changes as well. I'm not sure if this particular board has an on board speaker, so it might need a buzzer plugged in to get the beep/alarm code. Next make sure all the power leads / molex are plugged in securely to the mainboard and other components. Next I would try another another graphics card. Maybe borrow one from a friend? doesnt matter what type as long as it is PCIe based. Test your new components, ram / gfx card in a different known working machine (if you have one?) process of elimination back to the source. CPU is very rarely the cause of an issue, unless it has been incorrectly mounted. Carefully re-seat all the things. Power cables, Graphics card. Leave re-seating the CPU to last since that mucks about with the thermal paste, if you don't have any spare thermal paste that might be a problem.

I like the Xeon chips too although what you can do with it on the board depends highly on your BIOS/UEFI. good luck!

It may not be paging, Generally Windows works better with more than 4GB of RAM. Since your talking about a HDD, it could be disk fragmentation also (maybe try defrag?), if you've used a machine with an SSD in it everything else is going to feel slow regardless (Sorry). you might actually get more benefit from an SSD... Newer Windows 10 actually is pretty good with memory use, you can just open Task manager to see if its paging to disk (using heaps of memory), or whether its actually waiting for disk I/O (Read / Write), Perfmon (performance monitor) might be useful here to diagnose what exactly is causing the issue, have a look at the disk queues (Avg Disk Queue).

i5 4670k to 4770k isn't much of an upgrade, hyperthreaded processor cores don't scale 100%. 4930k/3930k is better, but ni no Kuni II's recommended specs are ivy bridge i7 3770k or AMD FX-8350 ... You're not far off that with the i5 so it should be playable, getting more cores than you need is a good thing which will help your multi tasking out. I'd pick the 4930k over the Xeon e5 1650v1/v2.. Xeon's don't overclock as easily, and the 4930k is clocked slightly higher. The x79 based board will be a much better platform for expansion, but the parts are quite a bit more expensive. (Processor and board mainly, don't go quad core if your using socket 2011 lol) 24gb of RAM looks like you're over the 8GB recommended, so that's fine ... and the GTX1070Ti isn't exactly a slouch either, it's already double the requirements of that game. OC to CPU with more memory might need more voltage to your RAM to remain stable, even if your not overclocking it. (I Had this issue with my Haswell rig, 4770k @ 4.2-4.4Ghz requires 1.56v for 1600MHz (32GB kit) Typically you can avoid this if you buy matched sets of RAM (Like a 4 pack that has been validated at the required speed) that doesnt gaurantee it will work though. What are you doing in the background for it to lag? You can try running it Fullscreen windowed mode and see if that nets you any benifit ( I guess your running dual screen or more since your multitasking), also disable the Fullscreen Optimizations in the advanced properites for the game and see if that helps. Also Turn off Xbox Game Bar if your running Windows 10, that will increase FPS as well.

it could be a mainboard fault.

I'm not sure if it would help, but I'd normally set up RAID0 in the chipsets boot ROM. (hit the 'I' (?) key during startup mode, your CMOS/BIOS will need to be set in RAID mode) Once the RAID array/volume is defined your disks will show as a single logical device under Windows. So you won't see two disk drive devices in Task Manager (AFAIK) If that drive is an SSD I wouldn't recommend running a Defrag. It can actually increase performance but it also causes a lot of wear on the SSD. For Hard disk drives, there is no such concern. Some older SSD's can have a positive performance increase by running a secure erase. I usually do this before re-installing Windows or other operating systems on SSDs. Always backup before making changes to your disk configuration.

Music production, I'd start with the case choice. Completely silent if possible. The Silverstone Primera RGB PM01 is a great gaming case, but due to the large mesh intake at the front you'd be leaking system noise out to the environment. I'd be picking similar components that you might find in a HTPC rig except more emphasis on processing power and memory. My go-to case for silent rigs is the Fractal Define series. I'd go fully passive for the graphics card, upgrade all the fans to Noctua. Wait a month or two for the i9 9xxx series CPUs to drop and also the 11xx/20xx series RTX graphics cards from NVIDIA. Corsair RMx i'd keep they are passive (noiseless) until under significant load. Get rid of the HDD and go fully solid state, something like NVMe Software Raid10 (4x NVMe SSD's like Samsung 980 Pro). Keep the 1TB Mx300 SSD and buy another one for RAID1 (O/S drive) The RAM will probably be compatible since it's DDR4, so you can also re-use that. If you plan to upgrade and keep the existing board and CPU, I'd focus on things that'd get your noise floor down to 0 or close to silent as possible. This makes most of the budget going into things like passive heatsinks and quiet fans. You could also go for a mineral oil dip solution if your feeling adventurous. Completely fanless

It's much safer to set a manual overclock and leave it, I had a play with setting all the power saving and other stuff on when I was setting up my PC. the amount of tweaking required to get it stable and to reduce vCore when down clocking wasn't sufficient in my Gigabyte board to stay stable, so I just left it at 4.2 if your temps are good at 1.35v under load and also stable, i'd leave it there. Unless your trying to get higher clocks. You need to establish what is causing the crashing, for me it was my memory on my Z87 board. The other things you can try is adjusting the System agent voltage up slightly. Use very small increments. (It sounds like you know what your doing anyway)

The more voltage you push in the CPU the more heat it will generate. If your cooling is adequate you can push more volts into it, if you aren't doing sub zero temps I wouldn't push it past 1.45v Intel Recommend no more than 1.52v https://www.intel.com/content/www/us/en/products/docs/processors/core/8th-gen-core-family-datasheet-vol-1.html, IMO that's WAY too high lol! Also while you might set 1.335 or 1.35 in your BIOS, the actual end voltage might be different depending on loading on the CPU and other settings (adaptive voltage, vdroop, stability adjustment parameters etc)

Max i'd say try to keep below 1.35-1.4v, you won't know what your CPU is capable of to achieve 5.1GHz until you incrementally adjust it up and test it. It's a long process, but in the long run its safer to explore the performance limits of your CPU this way. Leave the voltage at stock first and see how high you can go with the multiplier while still remaining stable. Start around 1.15v to 1.20v, see what you get!

@Pyranicus How are the temps with the Norco case and the 6TB Drives? I found the WD Red Pro 8TB / WD Red 8TB are too fat/tall for adequate airflow to go over them in this chassis ... I imagine the 6TB drive might be a tad less tall, the 4TB drives are fine ... but I wasn't forcing the air over them with Delta fans or anything crazy (With enough static pressure it'd probably work) I was trying to keep things fairly quiet ...

If your microphone is picking up sound in your room by the mic, the gain may be up too high. Make sure all the connections are tight for the headphones. After trying all these different things and you still have noise issues it could be a faulty headset. Is it still under warranty? Since you don't think it's the headphones, that really just leaves the mainboard/onboard audio ... You could try booting from a different SSD/HDD/CD (Live Linux or PE Boot with Audio) to test it out (Maybe it is software related?) I've found using a cheaper power board can introduce noise (humming/ ground noise and the like, but it doesn't sound like the issue your having), so make sure you have a decent quality power board (If your using one) and a surge protector.