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TweakTown's Ultimate Intel Skylake Overclocking Guide

By: Steven Bassiri | Guides | Posted: Dec 21, 2015 3:11 pm

Stability Testing


Stability testing is perhaps the most debated part of overclocking. Some say you are not fully stable unless you prove it by running Prime95 with AVX for two days straight. And on the other side of the spectrum, others are fine with testing the applications they use (like a game or video encoding program) and then calling it a day. I have even had debates with other TweakTown staff who say stress testing with AVX and AVX2 isn't really needed considering most programs don't utilize the extension (it adds a lot of heat), of course more and more programs are utilizing the extension for things such as video transcoding (Handbrake).



I think the roots of the stability label are taken to heart because everyone wants to overclock further than everyone else. For many people, overclocking is a competition even when there isn't a real competition. Obviously, testing with a tough stress tester for a few days will definitely decrease your chances of a random crash, but it also puts the CPU through a lot of stress, and takes a lot of time. For instance, when people run benchmarks for HWbot, their stability is just enough to pass their benchmark.




I tested stability on the best 6600K sample using three programs; Handbrake transcoding a 4GB video, 30 loops of Intel Burn Test, and Prime95 Small FFTs for 24 hours. This was perhaps the longest part of the OC guide when it comes to testing. I should also note that Handbrake doesn't raise temperatures like IBT or Prime95. In fact, you might not see the type of temperatures from Prime95 or IBT you might normally, and higher temperatures lead to lower stability as temperatures increase noise. Overall, it takes more voltage to pass harder stability tests as you reach the tipping point of your maximum CPU frequency on air.


Here are some Stability Tests:




CPU Delidding Results and Temperature


Warning: Delidding your CPU will immediately void the CPU's warranty, even if you have Intel's Performance Tuning Protection Plan.


It's no secret that Intel shifted from indium solder on Sandy Bridge to a polymer based paste for Ivy Bridge, Haswell, Broadwell, and Skylake. The reasons for this shift has been speculated to be cost related, but there is are much more scientific reasons which Intel explores in a paper from 2006 located here. The paper states that as the CPU die size decreases (which it has) to a certain point, indium/gold based solder for the thermal interface between the CPU die and the internal heat spreader (IHS) can cause the CPU die to crack after many thermal cycles. This study also makes sense because the server variants of these CPUs utilize solder based TIM instead of polymer paste like Skylake. Regardless, Skylake uses a paste which can be replaced with better paste to improve thermal performance.



There are multiple ways to remove the internal heatspreader and replace the TIM. Many people use a razor and others use the vice method (you can Google them). Caseking sells overclock der8auer's Delid-Die-Mate here, which is like a controlled vice method without a vice. The issue is that cost is high for single use purposes. There are services that offer CPU delidding for around $50 per CPU, but if you have a 3D printer or access to one, you can print a tool that can safely delid your CPU. I have printed the tool that can be found here and made a video of me using it (embedded above). If you want to print the tool, please use 50% or higher infill.




Results show that there is at least a 10C decrease in temperatures. A 10C drop in load temperatures is quite impressive, and this will improve as the thermal paste cures, and you can always use a liquid metal based paste like Liquid Pro or Liquid Ultra, which should provide lower temperatures. Rule of thumb for most platforms is that a 10C temperature drop can lead to a 50-100MHz CPU frequency gain, even when you are on the brink of your CPU's maximum stable overclock. High temperatures are a result of heat, and heat increases noise that decreases the ability for proper circuit operation. Noise can cause incorrect readings of high and low voltage levels.





You cannot succeed until you fail. The thing that people who succeed have in common is that when they fail, they learn from their mistakes.


If you cannot boot into Windows or even into the UEFI and your motherboard has a POST code display, your motherboard's manual can help you decode the listed two digit error code. Many times failing to post is a result of not enough voltage or failed memory overclocking. That is why I recommend you overclock the CPU core, followed by FCLK, cache, and memory - in that order.


Crashing: The motherboard, CPU, and PSU all have protection mechanisms in place to protect the hardware in your system. These protection mechanisms can cause crashing and throttling. If you system crashes suddenly, especially during load and just shuts down or restarts, then you have hit a trigger. The motherboard has trigger points in place when a trigger is breached the system is immediately shut down. Over current protection (OCP), over voltage protection (OVP), and over temperature protection (OTP) can immediately shut down the system if a trigger is tripped.


You can increase these triggers on most motherboards in their advanced VRM/PWM settings menu, and I have highlighted these menus earlier in this guide under each board's page. If your system is crashing by BSOD or an error code then that is usually instability rather than a trigger, you need to either increase voltage, drop frequency, or improve cooling.


Throttling: If your CPU frequency is throttling there are multiple causes. The first cause of throttling is high CPU temperature (usually over 90C), and that is a built-in CPU protection mechanism. The second cause of throttling is VRM temperature and/or current limits set in the UEFI under Turbo options. Many lower-end motherboards might have VRMs that don't have heat sinks and which are low in phase count, these boards are prone to overheating, and there isn't much you can do other than cool the VRMs.



Final Thoughts


Skylake overclocking is fun and is not too hard. Aim to keep temperatures below 80-85C when stressing with IBT or Prime95. Temperature will be your ultimate overclocking limit, and you will find that the maximum VCore you can set while staying under temperature limits is around 1.45v depending on cooling, and since Intel's operating maximum is 1.52v, I would stick under 1.4v for healthier 24/7 operation. If you want a quick OC, you can try 1.3-1.35v VCore with 4.5-4.7GHz with moderate LLC. I strongly recommend measuring VCore with a digital multimeter since CPU-Z is usually wrong depending on the board/brand.




I made this flow chart specifically for Skylake, and it has built-in recommended ranges. If you follow the flow chart, you should come out with a solid overclock. If you have any questions or concerns, please feel free to comment below.


Overclocking is more than just a way to increase speed and performance; it's a way to customize your hardware and run faster than anything sold on the market. However, be advised, overclocking can become addicting. It can become a journey that never ends, but one that can be very rewarding.


Stay classy my overclocking friends!

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