glenalz81

120mm rad for a 5800x isn't a good choice imo. i would go for a 280mm, or at least a 240mm. plenty of air coolers on the market that would out perform a 120mm as well.

Cheers man what a legend just got it there

Unless there's a particular reason you want it the RX 6600 is available atm for £350 which is the way i'd go.

https://www.cclonline.com/product/361216/RX-6600-MECH-2X-8G/Graphics-Cards/MSI-Radeon-RX-6600-MECH-2X-8GB-Graphics-Card/VGA6361/?dealevent=

Download the newest drivers for your card here.  Run DDU and completely remove your old display drivers. Disable your NIC so Windows doesn't try to automatically install your display drivers after you run DDU.  Run a few games or benchmarks and see if the issue persists.  

Those mounts screw down until they stop turning. Possibly has been a pressure issue.

Basically the cooler the 5800x the better. The AIO will see higher sustained boosts for longer and as for the fans it's hard to say but the difference will be negligable.

Basically the cooler the 5800x the better. The AIO will see higher sustained boosts for longer and as for the fans it's hard to say but the difference will be negligable.

PA120 (Peerless Assassin) will do just fine, go for it. 

I don't see Gelid Phantom available in my country, Malaysia. What do you think about the thermalright peerless assassin 120 dual tower cooler?
 

There is no universal setting anyone can give you that will just work. Every PC will work a little different, and every chip will react differently. 
 
If you having difficulty getting the settings figured out, I would advise not overclocking until you have a better understanding oh how to do it. 
 
Overclocking takes a lot of learning, a lot of patience, and a lot of time to do correctly. I have been doing it for over 15 years and I still spend about 15 hours every time I get a new system reading and watching videos on its specifics to learn the new changes. I would advice you leave it at default and go do more learning. Then, when you have gained more knowledge, try again 🙂

Did you clear CMOS?

Does the same thing happen at stock settings with no undervolt? And Have you tested any other games/benchmarks?

Does the same thing happen at stock settings with no undervolt? And Have you tested any other games/benchmarks?

Scythe Fuma Rev. B sits at 149mm and is a good cooler.

When switching GPU brands, you should DDU the old drivers before installing the new, otherwise there can be conflicts and problems as a result. 

6700 XT would be my recommendation.

6700 XT would be my recommendation.

Yep, unless someone builds a small form factor PC, using a single 120mm AIO for CPU cooling makes just a bad value/price ratio.
The CPU needs a 240mm AIO (2 fan radiator) to take full advantage of water cooling, otherwise a high quality air cooler is just better value/price for similar cooling performance.

Totally normal for a stock cooler with typical Ryzen behaviour.

A better cooler is option 1, option 2 is to set a negative offset voltage in bios, somewhere between -0.020 and -0.050. That will drop the spike voltage while maintaining performance in most cases. 

Check you have space for the Arctic 360, it's actually almost 400mm long.  I had 3 cases here, all with support for a 360 rad but the Arctic only fit in one of them. 😁

Performance wise i can't complain in the slightest. 

Yes it's normal. In high load, low current scenarios the voltage will be higher.  In high load, high current scenarios you'll soon see the voltage drop as the temp rises.

Check you have space for the Arctic 360, it's actually almost 400mm long.  I had 3 cases here, all with support for a 360 rad but the Arctic only fit in one of them. 😁

Performance wise i can't complain in the slightest. 

Yeah the 3900X is a b#tch. I had lots of trouble with mine too. I ended up using CTR to undervolt it and now it's fine.
CTR (Clock Tuner Ryzen) is a program made by some internet famous overclocker or something and the program helps stablizing Clock speeds and lowers voltage for each CCX so you get the best results.

It's also some work but after some reading you can do it.
 
 
EDIT:
https://www.guru3d.com/files-details/clocktuner-for-ryzen-download.html

From my experience it's almost always the case that's the issue with most cards.
 
The heavier cards tend to sag a bit naturally but the modern GPU's that are of decent quality usually have some sort of bracing on the PCB under cooler to help prevent sag.

This, I believe if your mobo.
You'll see a tab on the right side end of the PCIe slot, that holds the mobo in place
It has to be pulled away form the video card (downward in this image) to unlock the card.