Hi,
I'm an oveclocker but also a company which builds workstations (99.99% of work)
I have been beating records with CPUs all over the place. Corona, Vray, Kray etc.
The thing is: AMD Threadripper have some sensor which checks how fast CPU is getting hot changing states from C6 to C0 and P0 - core sleep and work modes.
If CPU is heating up fast the Perfect Clock (visible in CPU-Z will not be changed) but Effective Clock will be lower - HWINFO64
Do to only this fact the most benefit from good cooling are for 3970x and 3990x.
With bad cooling and high memory latency those chips are just expensive piece of silicon.
Considering long tests in Blender - as I do not have Corona.
3990x 64GB RAM 4 sticks 1600W PSU
Barbershop scene - Ultra settings and 4k Resolution.
AIR Dark Rock Pro 4 TR: 1h45m
LC 480+360 HWLABS GTX: 1h 24m
LC --//-- & OC @3.8GHz: 1h09m
The thing is that 3970x will do that test on LC in 1h33m
Just look at Corona benchmarks :
https://corona-renderer.com/benchmark/results/cpu/3990xWith a LC this CPU will run some about 3.2GHz by itself.
On air (open benchtable) Effective Clock can drop to some about 2.65GHz.
With OC @ 3.8 GHz and 33dB you can go all the time average 3.75GHz.
When silence is not the case: 38db, 4.15GHz and 4.1 Effective clock is maintained.
All TR3 39xxx series have TDP 280W. If you are to work on it efficiently accordingly to its price, than you have to have LC.
You can use AIR like Silver Arrow TT with 3 fans for 3960x and 3970x and you will be able to OC it a bit.
But 3990x is just a power and cooling hungry monster. And even with best air cooling you will not be able to maintain high effective clocks,
do to some internal heating up checking mechanism.
Cheers