Your iMac, CPU, and RAM are running at their lowest setting. How to solve it?

Question

iMac

Hello!
A little background:
In 2019, I bought a configuration:
iMac (Retina 5K, 27-inch, 2019) 3.6 GHz 8-core Intel Core i5, 8 GB 2666 MHz DDR4. Radeon Pro 580X 8 GB for music. In 2021, realizing that the computer resources are not enough for the tasks set, I decided to upgrade the CPU and SSD and RAM.
As a result, I got the configuration:
iMac (Retina 5K, 27-inch, 2019) 3.6 GHz 8-core Intel Core i9 processor, 32 GB 2667 MHz DDR4. Radeon Pro 580X 8 GB.

Problem of the following kind:

Recently, in the program Fruity Loops, when using more than one plugin, I noticed clicks characteristic of a small buffer. (Which is characteristic of CPU overload) I tried to increase the buffer width, but the processor overloads remained.

I started googling the problem and people on the internet suggested doing a couple of tests.
I downloaded the Geegbench5 program, started the test and was disappointed with the results. They were minimal. Then users on the Internet put forward a version that the test could be unreliable for some reason and advised to run Windows BootCamp tests from Windows, arguing that the architecture could be more CPU-friendly.

I also ran tests in Windows, the results of which disappointed me even more. Tests have shown that the processor operates at the minimum level, namely: 798MHz per core, instead of 3600 MHz. RAM also, instead of a clock frequency of 2666MHz, it runs at 1333MHz

I talked about measurements on the Internet and people advised me to reset the nvram parameters and then perform diagnostics using the "D" key after a reboot. I did all of the above, then repeated the test with Geegbench5 in MacOS, then in Windows, under Boot Camp. All tests also show the work of the CPU and RAM - at minimum levels. How to fix it? How to make the system work at cruising power? After all, now the system works at the level of iMacs of 2007.

In computers (PC) in the BIOS system, it is possible to influence the currents supplied to the CPU and RAM, change the operating frequencies, multipliers. Is there such a possibility in iMac? How to influence the explicit reset of CPU and RAM cruising values? What do i do?