Overclocking on the Z390 platform is pretty much the same as on the Z370 platform. So if you are familiar with that, overclocking your 9th gen Intel processor will be pretty easy. We are going to do all of our overclocking in the BIOS.
So in our BIOS the first thing we are going to want to set is the CPU Ratio mode to “All Core” and the “All Core” ratio to what we are going to shoot for. In our case it is 51, which will bring all of our cores to 5.1 GHz. Also if your BCLK is set at “Auto” it is a good idea to set it at “100.00”.
On the same page in the ASRock BIOS you’ll find your power limit and current limit settings. Motherboards have built-in power settings that will actually throttle your CPU if you throw too much power at it. To disable these built-in settings you can max out the “Long Duration Power Limit” and “Short Duration Power Limit”. You are also going to want to max out the “CPU Core Current Limit”, typically 255.50 is the max you can set here.
In your Voltage and power settings you are going to want to have a set CPU VCore voltage, we went with 1.35V. You may also want to test different load-line calibration settings.
While our system seemed to be pretty stable at these settings I noticed when I would put load on the CPU it would throttle almost instantly. Our temperatures were not all that hot so I was not sure what was going on. A good way to see why your Intel processor is throttling is the Intel Xtreme Tuning Utility (XTU).
Intel XTU told us that our processor was “Motherboard VR Thermal Throttling”. After doing some research it seemed our VRM components were getting too hot. Looking at the Phantom Gaming series the Gaming SLI/ac has much smaller VRM heatsinks than the Gaming 6 and Gaming 9 boards. We even brought the CPU frequency down to 4.8 GHz across all eight cores and we had the same result, which was a little disappointing.
We found a solution, which was placing two fans on top of the VRM heatsink, but obviously this is not a viable solution for most people.
I would say if you plan on doing any overclocking go for the Gaming 6 or Gaming 9 boards. With our fans cooling our VRMs we were able to achieve that 5.1 GHz overclock across all eight cores.