Nah, that’s a perfectly fine MB. Unless you’re doing a bunch of extreme overclocking stuff there’s nothing that board can’t do for you. The CPU and Pump header are rated at 3 amps so no worries there.
Honestly I think you’re worrying about nothing. The chips are designed to run at 95C. I get you’re worried about the rapid thermal cycling but they are designed for it.
Then make it appear so and at least provide us with the process that is spiking the CPU, because the solution to your more than an inconvenience might be as trivial as disabling GPU crashlogs or making exclusion in defender 
That is a reasonable responsible stance and i cant nothing but commend you for it. However right now we are discussin 7800x3d going to 85°C
anwsering your test: the lower heatspikes could also be because the 9800X3D design was restructured to place the V-Cache underneath.
And yeah maybe thats just how the 7800X3D works. Little heatspikes for nothing.
85c for a brief spike is harmless for a CPU like yours. They’re designed to withstand temperatures like that, up to 89c is the max safe temp for your specific CPU according to google and even then that’s not a problem since it’ll thermal throttle if it reaches that temperature thus protecting your CPU from harm.
So I wouldn’t worry about it unless its running that hot constantly for hours on end. CPU’s are actually one of the hardest components to kill from heat alone.
7800X3D does spike up and down rapidly because of it’s die design of slow heat transfer.
That’s why you see temperature suddenly go up and down when just browsing. This is normal.
Pump I leave at max and let motherboard decide AIO fans based on CPU temperature.
As the temperature varies so much and if you find the ramping of fans up/down annoying you can change the fan curve in motherboard to stage the fans i.e. 50-70C run at fixed RPM, then at 70-80C at fixed RPM higher to minimise variation.
With various Intel/AMD CPUs over the years I’ve stressed test IMC and put the CPU at full load overnights or whole days when doing RAM stability tests. It is same for people on overclock net forum which I source information from. They stress test for days and pin their CPU 100%.
This goes back to Helldivers 2 players raising issue of their CPU being damaged because of a game. This isn’t true, Helldivers simply stressed their CPU to reveal a problem they already had.
For sure. I also have a mild OC and undervolt. My point was by lowering my pump speed I was able to show a noticeable increase in temps when I quit the game.