bellabichon

Why would OP need to replace their PSU? 

G502 hero from Logitech. Was my first gaming mouse, and I still use it today. I have large hands, so it fits comfortably, and the programmable function buttons are really nice. 

It's enough for multiple applications
 
Fresh paste probably will not reduce your temperatures more than a couple degrees, what paste are you using now?
90 Celsius with a cooler like that, you might want to make sure your airflow is good and your cooler is mounted correctly. Good paste won't do anything if those are your problems.

I would suggest you reinstall Windows whenever you change platforms.

I would suggest you reinstall Windows whenever you change platforms.

Overpriced and the cases stink.
 
OP, I would go for an iBuyPower or Cyberpower prebuilt/custom configurator

i understand you're in freakout mode. but at this point you're getting too worked up, and need to take a break. 
wake up in the morning, watch some videos about it. try again. 
clear cmos, reflash the bios if you can get video. 

stop, go to sleep. relax. it will be there tomorrow. 

The Corsair CX-650W is a good unit for your build, and 650W will definitely be enough. Go for it. 

Different Thermal pad thickness??
 
I changed my gigabyte 3090 pads and core temp didn't change much, I measured and used the right thickness

No problem. List looks good overall, my only complaint is RAM. In 2021, 2400MHz RAM is pretty slow, especially on Ryzen. I'd go for this kit instead. It's only about $13 more for a decent amount more performance. As for monitors, 1080p 120/144hz would probably be the sweet spot for your config. I'd recommend something like the Acer Nitro VG240Y. It's 24", 1080p 144hz IPS for $200 on Amazon. 

You already bought a monitor at that price and weren't happy with it. What's going to change that now?

It's an unpopulated slot, so it should (physically) fit, but there'd be no way of knowing whether it would actually detect properly until you try. Looking around online, I can't find anyone with experience in BGA soldering who has actually given it a go.
 
So hey, if you're willing to become a pioneer (by possibly bricking your shiny new PC), go for it! Otherwise, you might just wanna buy a MicroSDXC card and shove it into the back. 

Sometimes you can switch platforms without reinstalling Windows, but the jump from Haswell to Zen 3 is so large that I'm not surprised it didn't work. I'd recommend you reinstall Windows on the system, then plug in your old drive to salvage any important files you want to keep. 

Motherboard, ram, AIO, case and power supply look fine. You should swap out the 3600XT for a 5600X if you can find one in stock, but I know that's a pretty big 'if' these days. Could also upgrade to a bigger SSD for more fast storage, but that's up to you. 
 
As for the GPU, I'm personally a fan of the Gigabyte Vision 3070 or 3080. The Asus Strix 3070 or 3080 is another option, but they're a little pricier than some other designs on the market. 

What are the temps like under full load? Ryzen in general idles hotter than most of Intel's chips, but that's not necessarily a bad thing. You could tune a more aggressive fan curve on the 212 if it's bothering you, though. 

I wouldn't recommend it. Nvidia says you should have 550W, and that's not the most solid unit out there. 

No complaints about CPU, cooler, motherboard, RAM or case. Could go for a little bit more on the SSD storage side, but if you're okay with slightly slower load times then don't bother. For power supply, I'd recommend you upgrade to the RMx 750W, as Nvidia recommends 750W for the 3080 (and you don't want to have to change out the whole thing in a few months). Last concern is the monitor. At 1080p, a 3080 is going to be crazy overkill. Unless you're planning to upgrade the monitor when you upgrade the GPU, I'd go 1440p with a higher refresh rate. 

People make a much bigger deal out of bottlenecking than I feel is warranted. Even in a well-thought-out system, chances are that either your CPU or GPU is going to be slightly faster, and that's fine. The only times real issues arise are when your budget is so poorly allocated that you're losing performance in the work you plan to do. My recommendation to you would be to determine your budget, read some guides and put together a PCPartpicker list, and then post it here on the forum for advice in the New Builds and Planning section. That way, people can help you re-adjust your choices if they think you could get more for your money.

Some extra-long zip ties should do the trick, and would last longer than electrical tape. 

People make a much bigger deal out of bottlenecking than I feel is warranted. Even in a well-thought-out system, chances are that either your CPU or GPU is going to be slightly faster, and that's fine. The only times real issues arise are when your budget is so poorly allocated that you're losing performance in the work you plan to do. My recommendation to you would be to determine your budget, read some guides and put together a PCPartpicker list, and then post it here on the forum for advice in the New Builds and Planning section. That way, people can help you re-adjust your choices if they think you could get more for your money.

People make a much bigger deal out of bottlenecking than I feel is warranted. Even in a well-thought-out system, chances are that either your CPU or GPU is going to be slightly faster, and that's fine. The only times real issues arise are when your budget is so poorly allocated that you're losing performance in the work you plan to do. My recommendation to you would be to determine your budget, read some guides and put together a PCPartpicker list, and then post it here on the forum for advice in the New Builds and Planning section. That way, people can help you re-adjust your choices if they think you could get more for your money.

People make a much bigger deal out of bottlenecking than I feel is warranted. Even in a well-thought-out system, chances are that either your CPU or GPU is going to be slightly faster, and that's fine. The only times real issues arise are when your budget is so poorly allocated that you're losing performance in the work you plan to do. My recommendation to you would be to determine your budget, read some guides and put together a PCPartpicker list, and then post it here on the forum for advice in the New Builds and Planning section. That way, people can help you re-adjust your choices if they think you could get more for your money.

What games do you play, and at what resolution? Definitely not the 3080 for $2500. That's highway robbery, even if it's $2500 AUD. Would you prefer to just get it over and done with, or could you do with a placeholder for a little while until things settle down a bit? Demand should come down eventually (fingers crossed). But if you're wanting to get the most performance per dollar ASAP, I'd say the 6700XT. 

What's your full specs? Sounds like a dead pump in your H100i. I'd consider six years to be pretty decent for an AIO tbh, but if you're looking to try something different I'd probably recommend the NH-D15.