ASUS motherboard by chance? Which BIOS # if ASUS?
In HWiNFO64, check your processor core list in HWiNFO64 Main>Central Processor drop-down>click on your processor. On the right column look for "Core Performance Order (CPPC)" (Listed twice, both should be same). The last two in the list, for my 5900X was core 8 & 12 (bios number will be 7 & 11). See picture.
Then go into your BIOS change those two to a 19, save & exit, get back into Windows and see if HWiNFO will round up the frequencies now.
I confirmed build v7.01-4420 that I could still make HWiNFO Sensors Core 0-11 Clock show **24.7-9, **49.7-9, or **99*.7-9 MHz variations if I changed one of the cores to an odd (or positive) while the rest of the number, in pairs were matched. In my case, a pair of even numbers on the core or paired odd numbers. Confusing, I agree, see list below.
My current ASUS PBO2 Curve is (number based upon BIOS, add +1 mentally to match what you see in HWiNFO Main but in HWiNFO Sensors the numbers will match the BIOS):
CCD 0 (per Ryzen Master): primary/best core, second best
Core 0-5 (all negative)= 18, 0, 20, 6, 20, 22
CCD 1: primary, secondary
Core 6-11 (all negative) = 22, 30, 23, 22, 25, 30
These are 2 cores I could run as odd numbers to get HWiNFO to show rounded up numbers based upon the .1MHz deviations created in the mV fluctuations in the BIOS. IF I had 1 odd or specific combination of all even numbers I would see the **24.7-9MHz through **99.1MHz on the HWiNFO Sensor page at Core 0 Clock-Clock 11 Clock. [These numbers are based upon my logging & preventing KERNEL-Power errors using HWiNFO to achieve stable 5.1MHz Boost. Your silicon lottery will not be the same as mine. However, running your strongest cores at that offset must mean you have lowered the Core Voltage of the processor. IF you have an ASUS board, on VCore Voltage Auto, you should see some outrageous core voltages in HWiNFO. Supposedly, research yourself, AMD says the 5000 series can handle it. Due to heat, power consumption & my goals for speed across all cores vs. single core speed, my VCore Voltage is manually set to 1.34375.
[Related if you have an ASUS MoBo: Did you set the negative 18 to all the cores under AiTweaker>PBO, where there is only a single option for all or Advanced>AMD OC'ing>Ok the agreement of destruction>Precision Boost Overdrive (aka PBO2)>Curve Optimizer Per Core? Are you getting KERNEL-Power errors (everyone says its a WHEA or black screen reboot) with random black screen restarts back to Windows login screen, when you go idle in Windows for a period of time?]