YouTube channel SkatterBencher recently published a video on how to overclock AMD's Ryzen 7 5800X3D processor, despite the chip being locked from conventional overclocking by AMD. In the video, Skatterbench managed to overclock the 5800X3D to an impressive 4.74GHz with all of AMD's voltage and multiplier limits in place.
For the uninitiated, AMD has purposefully locked out the Ryzen 7 5800X3D from conventional overclocking methods due to the 3D V-Cache technology the chip posses. AMD doesn't give exact details as to why the 3D V-Cache prevents overclocking, but there are a couple of variables that can cause potential issues.
One of the main side effects of adding 3D V-Cache is complications with heat, and additional heat generated from the extra cache directly. As a result, the 5800X3D runs hotter than AMD's conventional Ryzen 5000 CPUs.
Another could be an issue with the 3D V-cache's sensitivity to voltage, since AMD has limited the 5800X3D to a maximum voltage of 1.35v VID, which is significantly less than the 1.5v other Ryzen 5000 chips can utilize under optimal conditions.
Either way, this has not stopped overclockers from bypassing these restrictions and overclocking the 5800X3D. Since the core multiplier, along with Precision Boost Overdrive -- and the curve optimizer -- have been disabled or locked, this leaves base clock (BCLK) overclocking as the only other alternative to tune clock speeds. This is because the BCLK multiplier is controlled by the motherboard, not the CPU.
However, BCLK overclocking is a very inconvenient way of overclocking these days, as the BCLK frequency sets the frequency baseline for all other components on the motherboard, including RAM, USB ports, PCIe slots, SATA drives, NVMe drives, and more.
When you overclock the BCLK, you not only overclock the CPU but also the rest of the motherboard components that reference the BCLK. BCLK OCing is also prone to "RTC Bugs" that can inflate benchmarking scores as well.
The only exception to this is motherboards equipped with external clock generators. These boards can bypass overclocking all the components on the board, with the exception of the CPU and memory. However, these types of motherboards are exceptionally rare, especially on AMD platforms where every single CPU (with the exception of the 5800X3D) has an unlocked multiplier.
SkatterBencher's peak Ryzen 7 5800X3D overclock comes in at 4.74GHz, with a 104MHz BCLK. Overclocking was done on Asus' Crosshair VIII Extreme motherboard, with a custom loop running components from EK's Quantum watercooling lineup.
Thanks to voltage offsets and Asus's specialized Voltage Suspension feature, SkatterBencher was able to override AMD's maximum voltage output of 1.35v for the 5800X3D, to a maximum voltage of 1.375v.
Voltage Suspension is a unique feature offered by Asus that allows the user to set voltages against specific temperature targets, allowing the CPU to utilize higher voltages at lower temperatures, and pulling back voltage at higher temperatures to preserve the CPU's health.
In Prime95 testing with small FFTs and AVX enabled, the 5800X3D managed an all-core clock speed of 4.21GHz at 1.176 volts, with peak temperatures running at 93.4C.
With AVX disabled in the same test, that core clock jumps up to 4.36GHz on all cores and a voltage of 1.208, with temperatures hovering around 86-87C.
However, the CPU was able to achieve an absolute maximum core frequency of 4.74GHz under ideal conditions -- presumably under single-core workloads. This is a 240MHz frequency advantage over the 5800X3D's maximum default boost frequency of 4.5GHz.