I run mine with stock cooling it came with.  I have the cryo cooling on the CPU, and the stock air on the case fans and the 3080.  I have the gpu fans set at 75%, using MSI Afterburner to set those speeds on the GPU.  Using AWCC, I have the cpu fan set with an off-set of +50%, and the rest of the case fans have a 40% off-set.  

Under normal usage, i.e. not using synthetic benchmarks, it stays under 50c on the CPU and at 60c on the GPU.  That's when gaming in 4K.

Hi mate

1) Stick to default fan setting, I would start with Balanced.

2) You will need additional screws. The mother board has an additional header for a Cpu fan, so the choice is yours how you connect if you have a spare splitter.

It’s a straight forward process.

3) Paste mod is a must, I was really sceptical about the benefits but my temp drops were huge. You can lower your GPU fan speeds a lot after this mod.

I’m on a 3090 and my temps are no where near 60c on the GPU, that’s water cooling temps for a 3090.

But I guess it’s how much power the Gpu uses at the end of the day, 

Good luck with your new machine

1. The default fan settings is good? Shouldn't I have to ramp up the RPM on the Noctuas more to compensate for the 50% of the Dell stock fans?

2. Just 4 additional regular fan screws or do I need the 4 really long radiator screws? I browsed through the user manual and I don't see this extra cpu header fan. I do see 1 but isn't that occupied by the stock cooler fan already?

3. I thought about getting the 3090 but decided on the 3080ti instead. I kinda regretting it a little right now hahaha. From just a quick youtube search, it seems like the 3090 isn't that much faster than the 3080ti in terms of gaming power?

Agreed.  

As long as your temperatures are good you don't need to do anything or upgrade anything.

I would use it for a while and check your temperatures, before ripping things apart and potentially void warranty.

Be very mindful that purchasing the “upgrade” fans that you referred as they will surely be more quiet, however pay attention to the RPM speed.

The stock fans are 4K RPM and the Noctua you referred to are max of 2K RPM. There are different industrial Noctua that are 3K RPM but again still not as fast as stock.This is assuming you care more about temps and not sound.

I run GPU fans on 3090 at 75%, with 40% offset on all pc case fans in AWCC, and my GPU temps under load during 4K gaming are 58-59C with VRAM temps at 72C.

I have not repasted GPU yet as well so I would definitely try stock cooling first before you change anything.

Not only are these fans quieter, they also outperform stock fans. It wouldn't be much of an upgrade if they didn't. 

https://www.youtube.com/watch?v=W8W096R2wUk

12900 with a 120mm RAD @ 50deg 4k gaming??  Cough BS cough!

I've used several 280mm RAD's from Arctic, MSI and Corsair on the 12900kf and 4k /120 in ACC or Flight Simulator i'm hitting 60-68 with an outside air pull setup..  No way you're getting 50 deg gaming with mostly hot air in the R13 case and a 120..   

The GPU temps are more realistic.

Just keep in mind no matter what cooling upgrade you choose, it wont solve a high end CPU being instantly power throttled out of the box. Dell have also made it clear, they think doing that is acceptable and within Intel specs. Many would argue it is not, but Dell have decided otherwise and will not be fixing the issue.

In my experience the R13 is a good PC, It is certainly not the furnace mumbling Steve insists it is, but he finds fault with anything not made by Corsair his main sponsor. It rankles that Dell have taken shortcuts with the memory choice and power throttled the CPU but it is not half as bad as some of the You Tube "experts" claim it to be. For the non geeks it works perfectly well.

I watch GN for entertainment only.  Unfortunately people take his videos as gospel and pass on a purchase. His minions troll all across the net with their negativity.  Point is, run it first out of the box. If your FPS is good for you (it will be), than does not matter if the R13 is running hot or throttling. Sure it maybe underperforming to its potential specs, but at the end of the day it is working out for  you and that is all that matters. If it is not working out for you, then take the next steps.  I am not a gamer but content producer and the R13 with 12700kf and 3080 is lightning quick, runs cool, and is quiet.