WRITTEN BY Martijn Boonstra
Posted on November 06 2017
Since the day we started developing motherboards, we’ve always made sure to deliver maximum performance and beyond. One of the things that helps delivering just that, is LLC. You might have heard about LLC or Loadline Calibration some times, but what is it really and how can you benefit from it? In this article you will learn the basics of Load-Line Calibration and to use it to maximize the performance of your gaming rig based on any MSI X399, X370, B350, X299, Z270 or new Z370 GAMING motherboard. Also, why it's such an important feature when looking for the perfect 24/7 overclock settings for your CPU.
1. LLC, why is it needed?
2. Different levels of LLC
3. LLC in action: Don't overdo it
Chapter 1: LLC, why is it needed?
Until the introduction of LLC, when overclocking, we all had to deal with an annoying phenomenon called ‘Vdroop’ or ‘Vdrop’. Vdroop causes a slight drop in CPU voltage as CPU 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 5000MHz, the set 1.3v is delivered perfectly when idle, however, when testing stability through software such as Prime95 (can be with or without AVX) 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, resulting in strange behavior from applications and games and eventually resulting in a complete system crash. Effectively forcing you to apply overvoltage in idle, which uses more power, raises CPU temperature and speeds up CPU degradation when overclocking. Also, as you ramp up the CPU multiplier, the smaller voltage drop tolerance is allowed as increased voltage is proportional to CPU frequency, making it harder to push for the limit.
And so LLC was introduced to tackle Vdroop. LLC, short for Load-Line Calibration, applies additional voltage, when needed, to the CPU to ensure a more stable vCore under load (closest to what you manually set), and minimize the gap between CPU voltage in idle and load. So LLC is the golden setting when looking for the perfect 24/7 CPU 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 behavior such as overvolting on less heavy models. 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% or Mode 1, Mode 2 etc.).
↑The Z370 GAMING PRO CARBON AC comes with a 10-phase power design and LLC, ready for any OC.
To show how easy it is to tackle Vdroop nowadays we take the same setup, a MSI Z370 GAMING PRO CARBON AC motherboard coupled with an Intel i7-8700K CPU and set 'CPU Loadline Calibration Control' in the BIOS to 'Mode 1', which is the most aggressive setting. We set 1.3v vCore and overclock the CPU to 4.8GHz for 100% stability testing. We test with Prime95.
↑How to enable LLC on the Z370 GAMING PRO CARBON AC motherboard
↑LLC doing its job, keeping 1.3v CPU voltage under load (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 action: 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.
↑You can even use LLC when enabling ‘Game Boost’ 1-second overclocking
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 Z370 platform, LLC is more important than ever since we are now greeted with 6-core CPUs demanding perfect power delivery at high speeds.
LLC makes our lives easier, just find out for yourself and give it a try!
Fortunately, all MSI Z370 motherboards support LLC and a ready to take any Coffee Lake CPU to new heights. Available models:
- Z370 GODLIKE GAMING
- Z370 GAMING M5
- Z370 GAMING PRO CARBON AC
- Z370 GAMING PRO CARBON
- Z370I GAMING PRO CARBON AC
- Z370M GAMING PRO AC
- Z370 KRAIT GAMING
- Z370 GAMING PLUS
- Z370 TOMAHAWK
- Z370M MORTAR
- Z370 SLI PLUS
- Z370-A PRO
- Z370 PC PRO
Want to know about the most extreme Z370 motherboard? Check out Z370 GODLIKE GAMING video: