What is CPU VRIN

Overclocking know-how

Load-Line Calibration for optimal results!

* Basic information about overclocking can be found in this article, which presents OC results based on the MSI Z170 motherboard:
https://gaming.msi.com/article/skylake-z170-overclocking-experience-247-air-water-and-sub-zero-cooling-oc-results

Chapter 1: What LLC For? Fight against the Vdroop!

Prior to LLC's inception, overclockers had to overcome a disruptive hurdle called Vdroop. Vdroop causes the CPU voltage to drop as the load increases. The system then does not manage to maintain the set core voltage (vCore), which is required to keep the system stable. The CPU supply voltage drops under high load, which leads to crashes and blue screens. The most annoying thing was when the perfect setup was apparently found and it became unstable and unusable because of Vdroop.

 

An example that illustrates the negative Vdroop effects: The vCore is set to 1.3 V and the CPU clocks at 4.5 GHz in idle mode, the voltage of 1.3 V is brought to the CPU in idle mode without any problems. But when the overclocked system runs through various tests and benchmarks, such as Prime95, and the CPU is put under 100% load, the voltage drops to 1.27 V (or lower). The system becomes unstable and ultimately crashes. This forces you to put more voltage on the CPU when idling, which in turn leads to more power consumption, higher temperature and faster wear. And the higher the multiplier, the smaller the tolerance range for voltage fluctuations, and the more difficult it becomes to achieve the highest possible clock rate.

Defeat Vdroop
To overcome this hurdle, LLC was developed. LLC, short for Load-Line Calibration, provides additional voltage for the CPU so that the vCore remains stable. The tension gap between idle and load is minimized. LLC helps you get the perfect overclock result. But before you turn on LLC in the BIOS, you should pay attention to a few information.

Chapter 2: Various Levels of LLC

Since every motherboard has a different performance design, it is difficult to apply the same settings to different systems. The settings for a weaker mainboard do not necessarily work with a high-end mainboard. On the other hand, LLC can lead to unexpected results with high-end mainboards, for example unintentional overvoltages. In addition, every motherboard and processor reacts differently to LLC, so fine-tuning is a must for every system. That is why individual MSI mainboards even have different LLC levels (0%, 25%, 50%, 75%, 100%). To show how easy it is to set LLC on the latest motherboards, we take our MSI Z170A GAMING M7 and use an Intel Core i7-6700K as processor and activate the "CPU Loadline Calibration Control" in the BIOS by changing to "Mode1" ". We overclock the CPU to 4.5 GHz with a voltage of 1.3 volts. Again we test with Prime95.


Activate LLC on the Z170A GAMING M7 mainboard


LLC is activated, the voltage adapts

As you can see, we have a vCore value of 1.304 volts under load, exactly what was set in the BIOS. We also see 1.304 volts when idling. This is the perfect condition for overclockers who want to push their system to the limit and maximize CPU stability. You can see that LLC is a good friend when it comes to overclocking! Only the LLC setting "Mode1" is available for the selected mainboard. But, as mentioned earlier, there are also models with multiple LLC levels to choose from. What level do I then need to achieve 100% accuracy?

 

Chapter 3: LLC in Practice. Do not exaggerate!

Fine tuning is the key word. Check which settings are best for your system to prevent Vdroop without overloading the CPU while idling. In most cases, a 50% or 75% LLC will do. For extreme overclockers, the test with the 100% level is also worthwhile, but this causes a very high overvoltage in idle. Finding the right settings is the key to overclocking success and a stable system. However, it should be noted that an increased core voltage can reduce the service life of a CPU. While LLC is great, it should be used with caution.

Conclusion

For a stable system when overclocking, it is highly recommended to enable LLC in the BIOS. LLC helps you to get the last bit of performance out of your processor and at the same time keep it stable. Even so, LLC must be used with caution as excessive settings can put too much power on the CPU and potentially shorten the life of the CPU. LLC has more influence on a Z170 mainboard because the CPU voltage regulators are implemented on the mainboard. That was not the case with Haswell, the converters are located here in the CPU.
Overall, LLC is a great feature that you definitely have to try out!