You should have performed your tests with the latest official BIOS "4.03" because the "3.02" with which you performed your tests is clearly buggy (in addition to using a fairly old version of the AGESA AM5 firmware), because it limits CPU performance (because of the STAPM bug that throttles you) and iGPU, it is limited because of the STAPM bug too but there is also another problem that is added to this one and which was only corrected in the latest official BIOS "4.03". And frankly it's also a shame that you didn't exploit the potential of this little bomb (when it is well equipped and adjusted) by installing a more efficient heat sink than the one supplied originally (which is only present in the bundle to help you out if you don't have one) like a Thermalright AXP90-X47 (see the "full copper" model which dissipates up to 140 Watts of TDP officially) and in the "Performance Mode" (equivalent to "PBO On") in the BIOS to let your Ryzen 5 8600G express all its performances.
There is also an "unofficial" variant (but coming from the ASRock BIOS department) of the latest BIOS "4.03", the test BIOS "4.03.MEM01" which unlocks access to the DDR5 SO-DIMM RAM voltage settings, settings which will finally be "officially" available in the next final BIOSes that will be released for the DeskMini X600 (source: an email received personally from the ASRock BIOS department), this test BIOS is perfectly stable and has allowed me so far thanks to these accesses to the DDR5 SO-DIMM RAM voltage settings, to overclock my Kingston FURY Impact 6400MHz CL38 DDR5 SO-DIMM 32GB (2x16GB) kit up to a perfectly stable 8000MHz CL38, this allowing me to drastically increase the performance of my iGPU "Radeon 780M" of my Ryzen 7 8700G, by about 40-50% depending on the game thanks to the extra DDR5 RAM bandwidth.
The test BIOS in question can be downloaded here:
Greetings to the users of the DIY MiniPC ASRock DeskMini X600, I am opening a thread here for those who wish to have the possibility of adjusting the voltages of their DDR5 SO-DIMM RAM kits (I know for a fact that you wish to do so) as well as the vSOC, so I am sharing with you a link to...
smallformfactor.net