Aurora R15, throttles down to 0.786 GHz

What are your rig components? Temperatures appear "normal" . . . is that Fahrenheit or Centigrade? What happens if you run Cinebench R23?

Run prime95 blend stress test, and check temperatures and frequencies while it is running.

Prime95 

I just tried that CPU-Z stress test and went to immediate high utilization and frequency. I am testing an i9-9980XE and your CPU has the very latest architecture . . . so not sure about any reasonable comparison.

Hi,

The processor is an  AIO liquid-cooled 13900kf, 64GB Ram; rtx4090 graphics.  At start-up with the higher clocks the cpu temps are about 35-45 (C) and when the system goes to .768 GHz the cpu temps are about 35C, no fan noise.  Just scanning the components overall, no temps seem high at all.  I haven't run cinebench.  I stressed the system with a feature that comes with cpu-z, beginning when the system is at the .768 GHz.  When starting the stress test, the cpu utilization slowly increases but the cpu speed stays the same.,  After a couple of minutes the speed rapidly increases to 3.0 GHz and holds there.  On my other systems, use of this stress cpu feature results in a nearly immediate transition  to high cpu utilization and clocks.

So, I tried the cpu-z test before the system goes to the 786 MHz, so its running variably across cores at about 4.3 to 5.8 Ghz.  Then I start the test:  The processor immediately goes to about 16000 on the cpu multithread which is about the same as the current amd 7950x part and the clock is about 5 Ghz.  I hadn't tried the stress test when the system was showing "normal" clocks.  The the system went down to 786 MHz and I ran the same test again.  This time the performance only slowly increases and doesn't get above about 8000 on the multi Tread result (half of before) and begins throttles down to stay about 3 GHz.  This was the typical result when starting at 786 GHz.  The only way I know to get back to higher base clock when the system gets into this state is to turn it off and wait a while.  The P core E core temps are 33 C and 35 C. I have never encountered anything remotely like this behavior.

IT should boost instantly. You can try loading BIOS defaults, or release the fleas. Flea release 

Fleas work but only for one boot and only for 5-10 min;  When the system seems noral for the first few minutes, the stess test reponds instantly with high (16000) multi-tread scores; later when the system is at 786 MHz, the same test only achieves 7500 scores (beginning at 2200) and even at 100% cpu utilization stay for a couple of minutes at the low clock rate before inching up to 3 GHz at 7500 before brief throttling due to 100C on P cores.

Maybe a new cpu would help?  I also noticed that the cpu voltage in the latter stress tests was only .9v (min-.7;max=1.5) and would have thought that under stress, more voltage might be expected to drive the cpu that hard.   

Sounds more like a motherboard issue to me, than a CPU issue. It's rare for a CPU to fail.

The high end R13 range power throttles the CPU to keep it within temperature range. Imagine my surprise to learn that in a slightly different way the R15 does the same thing. I don't think you have a faulty MB or CPU, I think you purchased a PC that power throttles to keep its components cool enough. 

Am waiting for the 4090 / 750W power supply owners to report in on what Dell slowed down to get it to work. Theoretically it will but is far from the ideal combination. 

It should not throttle down to 0.8 Ghz... Should at worst throttle down to base frequency.

Enjoy your new rig!

Thank you! And thanks for your help!