WereCat

Overclocking the memory specifically in case of 7900 GRE as that is the most limiting factor on this card.

For $130 that's not bad. Look at what kind of performance to expect from that and decide if that can last you 2-4y for your needs before you need to upgrade again.

1.) Update BIOS before swapping CPUs 2.) Reset CMOS after swapping CPUs then reconfigure your XMP/DOCP profiles no need to reinstall Windows. MAYBE reinstall chipset drivers but even that shouldnt be necessary.

save up for a new platform. Spending anything more than 100eur for your system is just a waste (and even 100eur is arguably too much). You can probably find 2nd hand used 3000 series Ryzen along with a motherboard and RAM for 200eur these days.

You can save 20eur by going with 7600 instead of 7600X... if you enable PBO in the BIOS they are basically the same CPU Then you can change RX 7800XT to RX 7900 GRE and the total price will be around 28eur more but you'll have better GPU https://nl.pcpartpicker.com/list/sc4nVW

That's either a really bad cooler contact or bad paste application/dry out/pump out

This. VSync is "required" with GSync as in some cases there may still be some minor tearing near the bottom of the screen. If you don't have VRR display then you can use FastSync (NVIDIA) or EnhancedSync (AMD). This eliminates tearing ONLY if your FPS is higher than your monitors refresh rate. It still ads input lag but way less than VSync and the higher the FPS the less input lag you'll get.

what is the power usage during the spike and how many cores are active at the same time?

I don't know but I also don't know what you want. Which codec? How many video streams at what resolution and refresh rate? etc... "max performance" in this can mean anything

IMO the 7800X3D even with just 4060 is a good choice. If he does not need to run high graphical fidelity the extra CPU performance will be nice especially for the sim games. I'd rather look at what else besides CPU you don't really need that much to get a bit more GPU budget.

Which game? Also looks like you did manual CPU OC and therefore reduced max CPU boost clock by around 400MHz.

If it crashes your display driver then all monitors will go black.

Also if you have faulty display cable it's known to caue flicker or outright driver crashing with 5000 series RDNA cards.

Getting 4 sticks of DDR5 working on Ryzen has always been tricky. As I haven't even touched any AM5 parts yet I can only speculate but in my case on AM4 with 4 sticks I have to increase DRAM Current Capability from default 100% to at least 120% otherwise my system will randomly shut down. Maybe you can do it too (but would have to boot with 2 sticks, set it up, turn off PC then insert remaining sticks and try to boot again). You may also need to bump up SOC and VDDP voltages slightly from default. Watch out with the SOC though as you don't want to go 1.3V+ if you're already there!

Can't really compare that as both systems are wildly different. I get what you're saying with the avg FPS being higher on your friends PC but that can be a run to run variance as I mentioned the game performance varies wildly depending at which stage of match youre in, where on map you're located and how many people are nearby. You would have to test the identical scenario every single time to make a more fair comparison as you can have like 50FPS+ run to run variance in PUBG depending on how you test it. His GPU is slower so he will be pushing it harder and thus will have higher GPU usage most of the time than you. His CPU is basically the same as yours. The extra cores you have are not really relevant for PUBG and you will hardly notice a 100MHz difference in boost performance.