Why LLC is your friend when overclocking


Posted on February 01 2016



Like to overclock?

Load-Line Calibration will help you out!

What is Load-Line Calibration?

In this article you will learn the basics of Load-Line Calibration, or LLC in short.

Also why it's such an important feature when looking for a suited 24/7 overclock of your CPU.


  1. LLC, why is it needed? Battle Vdroop
  2. Different levels of LLC
  3. LLC in practice: Don't overdo it
  4. Conclusion


*In case you want to know more about the basics of overclocking or want to compare OC results using MSI Z170 motherboards on air, water or sub-zero cooling, you can check out this article: https://gaming.msi.com/article/skylake-z170-overclocking-experience-247-air-water-and-sub-zero-cooling-oc-results

Chapter 1: LLC, why is it needed? Battle Vdroop

Until the introduction of LLC, when overclocking, we all had to deal with an ugly beast called Vdroop. Vdroop causes a drop in CPU voltage as load increases. The system is unable to maintain the set vCore perfectly, needed to keep the OC setting stable. CPU voltage would drop under system load to a point where frequent BSOD's (blue screens) or crashes occur. It was especially bad when you thought you've found the perfect 24/7 OC, Vdroop would come and spoil the fun by making your system unstable.




An example of the bad effects from Vdroop: you set 1.3v CPU vCore to reach a stable overclock of 4500MHz, the set 1.3v is delivered perfectly when idle, however, when testing stability through software such as Prime95 and putting 100% load on the CPU, this voltage would drop to 1.27v (or even lower in some cases) and your system would become unstable and crash. Effectively forcing you to apply overvoltage in idle, which uses more power, raises CPU temperature and speeds up CPU degradation. Also, as you ramp up the mulitplier, the smaller voltage drop tolerance is allowed as increased voltage is proportional to CPU frequency, making it harder to push for the limit. 

Defeating Vdroop
And so LLC was introduced to tackle Vdroop. LLC, short for Load-Line Calibration, applies additional voltage to the CPU to ensure a more stable vCore under load and minimize the gap between CPU voltage in idle and load. LLC is the golden setting when looking for the perfect 24/7 overclock. But before you go on enabling LLC in your systems' BIOS, there are a few things you need to know.

Chapter 2: Different levels of LLC

Since each motherboards' power design is different this makes it difficult to create 1 setting which would flatten the drop to match it with the vCore set. As you can imagine, a perfect implementation to less powerful motherboards might still not be sufficient for more high-end gaming & dedicated overclocking models (which use different brand power phases and higher quality components). On the other hand, LLC on a high-end motherboard can lead to unwanted behaviour such as overvolting on less heavy models. Also, since each motherboard and CPU configuration might react differently to LLC it's hard to design 1 setting of LLC which is spot on, covering all configurations. This the reason why you'll see multiple settings in the BIOS when looking at LLC for some motherboards (0%, 25%, 50%, 75%, 100%).  To show how easy it is to tackle Vdroop nowaydays we take the same setup, a MSI Z170A GAMING M7 motherboard coupled with an Intel i7-6700K CPU and set 'CPU Loadline Calibration Control' in the BIOS to 'Mode 1'. We set 1.3v vCore and overclock the CPU to 4.5GHz. Again we test with Prime95.

How to enable LLC on the Z170A GAMING M7 motherboard

LLC kicking in, maintaining 1.3v CPU voltage (click to enlarge picture)

As you can see we now get 1.304v vCore under load, which is exactly what we set in the BIOS. We also see the same 1.304v vCore during idle. This is the perfect scenario for any overclocker to push their system and maximize CPU stability when doing so. Proof LLC is really your friend when overclocking :) For this specific motherboard used in the above testing, we only have 1 setting for LLC called 'Mode 1'. However, as mentioned earlier, there are also models which have multiple LLC settings to choose from. So which setting do I need to achieve 100% the same voltage as set?


Chapter 3: LLC in practice: Don't overdo it

Fine-tuning is the keyword here. Check which setting works best for your setup, stopping the vdroop effect without overvolting when the CPU is idling. In most cases a setting of 50% or 75% LLC should be enough. Extreme overclockers might look at the 100% setting, which in most cases causes to overvolt heavily when idle and slightly under load. Finding the right setting is key to ensure your overclock will remain stable under any condition. However, be careful with overvolting your CPU for 24/7 usage since using higher voltages it is said to degrade your CPU quicker (read: lowering its life expectancy), going above a certain point. Although LLC is great, you should use it with care, like you should do with applying higher vCore to your CPU.  



When overclocking, especially to find a nice 24/7 overclock, always be sure the LLC setting in the BIOS of your motherboard and turn it on. LLC can really help you get a few 100MHz more out of your system while improving stability when overclocking. However, as for overclocking in general, LLC should also be used with care. Some motherboards and configurations might overvolt the CPU in some cases, degrading the CPU quicker when going over certain voltage limits (also depends on the cooling used). On the Z170 platform LLC has more influence again since the CPU voltage regulator is implemented on the motherboard, whereas for Haswell, this was on the CPU, making LLC virtually impossible from motherboard side. LLC makes our lives easier, just find out for yourself and give it a try!





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