I bought a new Alienware Aurora R12 from Best Buy 5 months ago in July of 2021. It was a major step up from my last computer, that had an i5 with an integrated UHD 620. I had very little problems at all with anything. Alienware made everything super easy to figure out how to control the RGB, Fans, etc.  

Problems didn't start happening until around the start of November of that same year. I bought Mafia 2: Definitive Edition and decided to play the Classic version, as it came with the purchase. Anyway, I played for 5 hours straight with all my fans at 50% on accident. The next day I started up the Definitive Edition and was faced with minor lag spikes, around 20fps dropped from 60fps so between 40-60. It made me a little irritated considering I spent a fortune on this computer. I later played Sea of Thieves with some friends, a game that usually ran at a smooth 60FPS on Mythical Settings, and the game was lagging, around 55-60fps. This problem persisted in every single game that I own: Sea of Thieves, Assassins Creed Odyssey, CS:GO, Dead by Daylight, Destiny 2, ES4 Oblivion, ESOnline, Garry's Mod, GTA 4, Halo MCC, Mafia 2, Phasmophobia, Civilization 6, and even Terraria, for christ sake.
The problem has only gotten worse over time, Halo MCC that used to run at 120fps started playing at 70-120fps but now it plays at 40-118fps

What I've tried:
-Updated Windows / Drivers / BIOS / Chipsets / etc.
-Used DDU many times

-Went to Geek Squad and other 3rd party shops (to have them physically inspect and nothing is wrong)

-Completely reinstalled Windows many times (and upgraded to Windows 11 then downgraded back)
-'Sanitized' SSD and HDD then reinstalled Windows via external HDD
-Tried every Game Ready Driver from October 2020 to most recent, as well as the most recent Studio Driver
-Called Dell Tech Support, had a Remote Session and setup an 'on-site' repair, getting a brand new RTX 3070 installed, under warranty, yet it didn't resolve the issue.
-Used multiple Benchmark tests with all of them passing
-Playing at Lower Settings with a Lower Resolution with the same results
*ALL games play the same, no matter the settings. It just lags more consistently when I turn the settings up.*

Specs:
Processor 11th Gen Intel Core i7-11700F 2.50GHz
Graphics Card NVIDIA GeForce RTX 3070 (8.0 GB)
Memory 11.4 GB Free (15.7 GB Total)
Monitor Generic PnP Monitor (1360x768 60 Hz)
Disk Storage 2668.3 GB Free (3032.3 GB Total)
Audio NVIDIA High Definition Audio
Motherboard Alienware (07W25T)
Mouse HID-compliant mouse
Keyboard HID Keyboard Device

(more details on GPU)
Name NVIDIA GeForce RTX 3070
Video Processor NVIDIA GeForce RTX 3070
Manufacturer NVIDIA
Video Architecture VGA
DAC Type Integrated RAMDAC
Memory Size 8.0 GB
Memory Type Unknown
Video Mode 1360 x 768 x 4294967296 colors
Current Refresh Rate 60 Hz
Driver Version 30.0.14.7284
Driver Date 12/20/2021

I have seen a lot of people with my same issue on MANY different forums, I have had many professionals look at my PC inside and out. I have truly exhausted all my options for restoring my game performance to its original glory, it was a good 3-4 months but at this point I'm either going to build a new computer using these parts once I can get a new motherboard, or I will sell it pieces as I can get good money for an RTX 3070 and 11th gen i-7 11700F and I don't want to mess someone over, as I have reinstalled Windows many times I feel it would persist with someone else.