Intel i7 14700K CPU Speed Drop during Corona Render

[artikedu]

Hello,

This is my problem:
Intel CPU reaches around 5,20Ghz during normal performance, but when I start any kind of Corona render it (almost) drops to the base speed 3,40Ghz.

Running:
Corona 11

These are my specs:
- System: Windows 11 Pro Version 10.0.22621 Build 22621
- Motherboard: Z790 AORUS ELITE AX rev 1.1
- CPU: Intel Core i7-14700K, 3400 Mhz, 20 Cores, 28 Logical Processors
- Memory: 128GB DDR5 running at 5600 (Corsair 128 GB DDR5-5600 Quad-Kit)
- GPU: NVIDIA GeForce RTX 3070 Ti

Tried:
Updating bios, reinstallation of Windows, Corona and 3dsMax.
 
All render settings on default, no difference. Also no difference between a clean 3dsMax install or a modified one with plugins (ran the Corona Benchmark to make sure).

The CPU does seem to be running at 100% during render, but not at the expected speed (see attachment).

Thanks in advance for any insight!

[rowmanns]

Hi,

This sounds like it could be thermal related, what kind of temperatures are you reaching when rendering?

Cheers,

Rowan

[romullus]

Did you try to run Corona benchmark and compare your score to the median of other users submitted results with the same specs machines? https://corona-renderer.com/benchmark

[artikedu]

Hi Rowan,

Thanks for your reply!

I did some tests over the weekend and it indeed seems to be a thermal problem.

CPU reaches 95-100°C immediatly when starting a render.

I have a Dark Rock Pro 4 CPU cooler installed, but due to the size of the RAM one fan is sticking out a bit (see attachment, I can't even close the case properly).
Since discovering this issue I've ordered NZXT Kraken 360 and the NZXT H6 Flow case. It should arrive somewhere this week. I'll run some tests then and see if it solves the issue.

Did you try to run Corona benchmark and compare your score to the median of other users submitted results with the same specs machines? https://corona-renderer.com/benchmark

I did try, but it seems other systems closest to mine are running with an i7-14700KF, not an i7-14700K.
The highest I've reached you can find here: https://benchmark.chaos.com/corona/v10/scores/4518
Closest to my build would be this one: https://benchmark.chaos.com/corona/v10/scores/3683, which reaches about 1.15Ghz more and is 2.760.456 rays/s higher.

[rowmanns]

Hi,

Yeah, it does sound like thermal throttling.

I think that cooler, even configured like that, should do a better job of cooling that CPU than it's currently doing. Maybe it's worth re-pasting and re-mounting the cooler.

Cheers!

Rowan

[artikedu]

Hi!

Cooling was indeed the issue. I've installed the new parts today and ran a benchmark. CPU temp when benchmarking was between 70-75°C.
Benchmark results: https://benchmark.chaos.com/corona/v10/scores/4554

Thanks for the help!

PS: Cooling paste/Cooler surface was not connecting good with the CPU in previous build due to the size of the RAM. This most likely caused all the thermal issues.