Maybe the cooler/cpu not properly seated? Mine usually max around 75c though mostly hovering around 72c. I've not played the games you listed but Total Wars are pretty CPU intensive games.

You can boot even when not installing fan 😁 but probably temp will straight go to 100c.

I mean maybe one of the screw no tighten properly. Did you use the thermal paste that comes with the cooler or after market one?

Air ventilation may also caused high temp. Before I use ryzen, my i5 was running pretty hot until I added 2 fans on the top of the case.

Can you try open side panel? That case look like it doesn't have any airflow.

It does, but maybe he doesn't install any
There are lots of fan mounting options in the case

Front: 3x120MM or 2x140MM (not supplied)
Rear: 1x120MM (supplied)
Top: 1x120MM or 1x140MM (not supplied)

Lineage referring to the above, install some fans for the intake
Install either 3x120MM or 2x140MM in the front

Try to reinstall the cpu fan with after market termal paste.

Install more fan if temp go down significantly when you open side panel.

Install another 120MM for the intake

Yes
Also since you are not going to overclock, buy the cheapest 3rd party heatsink out there, such as Cooler Master Hyper 212

Definitely
Also, manada 100+. Less than RM100 in Shopee

Link - https://shopee.com.my/Cooler-Master-Hyper-2...87129.823445085

Can you try open side panel? That case look like it doesn't have any airflow.

Install more fan if temp go down significantly when you open side panel.

One single fan can hardly improve.
, you need at least 6 fans to improve ventilation.
The case i bought always has side panel fans, and top panel fans, 3 front intake is a must.
Even with stock cooler my 65w Ryzen only idle at ~37c, 40 to 50 on load.

With my Fractal design R6, my cpu idle at 32c (360 aio), Vega 64 idle at 36c only.

Also make sure the CPU Vcore is not set too auto, some board will increase vcore without good reason, like my B350 Mortar arctic,
The increased vcore will increase heat output as well.

What is your case?
because intake usually is filtered, meaning weaker air flow, that is why intake need at least 3.
one single fan can improve only if it's high airflow fan, Aka the infamous Delta, usually known with at least 260 cfm lol

or just upgrade your casing

If I were you I will try the cheap way first, either add 2 more 120mm front fan, or swap them for 2x140mm.
If that fails, then I will consider AIO or changing the case for another with better optimized for running stock/aftermarket air CPU cooler.

You CPU is definitely recycling those hot air from itself and the GPU. I think the additional fans intake on the front pay will help, but do note that it will not be as good as open case.

I will take the high SP ones because I can reuse them as fan for radiator in the future, that's just me. It's perfectly fine to take the AF one.
I agree 2x 140mm because even though 3x120mm moves more air, the 3rd bottom fan only cools the self contained compartment below.

If me, i will go with the cheapest option... remove the side panel permanently.

3 months later back with square one, because heatsink is full of dust lol

Delta fans with PWM can be tamed with pwm + 45 watt fan controller, but if your delta is 3 pins type, can only be used as emergency cooling lol (activate when temp reach critical.)

you can add 2 140mm fans but with at least 2000 rpm, larger fan has lower pitch noise than 120/92mm counterpart, but with lower static pressure.
top fan can be switch to intake, at least the cpu has fresh air. and rear exhaust remain same, but remember, hot air rise.

https://noctua.at/en/nf-a14-industrialppc-2000-pwm Noctua IndustrialPPC 2000rpm 
https://noctua.at/en/nf-a14-industrialppc-3000-pwm 3K rpm versioon
https://www.silverstonetek.com/product.php?pid=366&area=en this one is 38mm thick, so check clearance first.

Most people be like, i got R6 2600 and some thousand dollar GPU but using cheap casing,  later will complaint pc running too hot.
Case cooling performance are most often ignored when people buying new casing.

Open air casing depends on environment, my area definitely cannot due to sticky yellow dust, it does not work with everyone.

Also buying the Noctua definitely is an investment, the fans has 6 years warranty and very long life, Thought Im only like noctua lol,
also i'm not aware of any other brands that make 140mm fan with 2000 RPM.

You do not need to worry about the CPU temperature.

Ryzen runs at low temperature with pathetic OC headroom.

So,
1) You do not need Noctua. Just mid-end HSF will do. You don't get much OC headroom anyway. The reason is the CPU itself.
2) You do not need to buy expensive casing. Cheaplug casing with 2 x 120MM casing fans + PSU fan is more than enough.
3) Spend the money on high quality motherboard. I would say most of low-mid end mobos have shitty and overheat VRM. High quality mobo gives you stability and very slight better OC headroom (again, the limitation is the CPU itself).
4) Spend the money on high end ram modules. You get more performance penalty if you use low end ram modules. Get high end ram modules for performance.

You have decent ventilation with 2*120mm fans.
It is an overstatement claiming the heat traps in your casing with 2*120mm fans installed.

You don't need to cool down CPU more, not for Ryzen.
As I said, 2 reasons,
1) Ryzen is not a hot chip. It doesn't generate much heat. What's there to cool?
2) Ryzen has extremely poor OC headroom. Having premium HSF doesn't give much OC headroom. The limitation is the Ryzen chip as it just doesn't give you much overclockability.

Spend your money on high quality ram modules if you do not want 10-20% performance hit.
Spend your money on high quality motherboard if you overclock. VRM and system stability remains a problem with cheap AMD motherboards.

Sorry, I don't read all the posts.

Stock HSF? Overclocked? At what speed?

Assuming it is overclocked at 4.1GHz, leave it as it is if you don't encounter any stability issue.
Changing HSF doesn't give you much OC headroom.

Problem is the stock cooler.
Not the ventilation of casing.

Get a mid-end HSF.

I will test it (Ryzen 5 2600) later today and let you know if I encounter the same.

What casing are you using again?

Nowadays it's all about aesthetics, many casings have garbage ventilation/airflow to feature glass/acrylic side panel while having poor front intake even on some high end case.

That guy definitely have airflow problem because he mentioned temperature dropped significantly when he opened the side panel.

Ryzen stock cooler is great, much better than shitty Intel one. Suggesting him to buy a  new HFS is pretty pointless imo.

I saw your post that 10c  temperature difference with side case panel opened.

Did you even install fans in casing?
How many 120mm fans you installed with above setup?

Both CPU and GPU seem to have high temp at idle, especially they run at stock clock.