Intel Max Voltages Stability Testing
There are only two things you can do to help stabilize higher clocks. The first is to raise voltages, and the second is to improve cooling. Improving cooling is the best method to increase clocks and stability, as it only helps. Improving cooling is difficult and costs money, but increasing voltages is free. However, increasing voltage can also increase instability as the added heat and heat noise can affect stability. It's a double edged sword.
You can delid your CPU, use a custom water cooling loop, change thermal interface material, and even go sub-zero. You might find that reducing voltages lowers CPU temperature enough, so something like 1.3v could be stable while 1.4v would cause instability at the same frequency because of the added heat.
Intel recommends a maximum operating voltage of 1.52v VCore, but that's just way too high. I don't know of any watercooler that could cool down a CPU being fed 1.52v, but of course, that figure from Intel doesn't account for LLC since it's not part of Intel default specifications. I recommend 1.45v as maximum VCore with non-subzero cooling, but that doesn't matter since you will probably hit a thermal limit before you hit that voltage limit. The VCCSA (System Agent) is 1.05v stock, and the VCCIO (System IO) is rated 0.95v stock.
Even though Intel says maximum VCCSA can be 1.52v (which is a new addition to the 8th/9th generation datasheet) I recommend no more than 1.35v on either VCCSA not VCCIO. I honestly wouldn't run much more than 1.25v for 24/7 use. If you hit an issue with DRAM overclocking, try many different levels from 1.1 to 1.35v. I have seen memory controllers that don't like anything over 1.25v, so try increasing VCCSA first and then VCCIO, and it's fine if they are different levels.
Here is our 9900K chiming in at 5.2GHz with a 0-AVX offset, which when combined with Handbrake, which uses AVX, produces a pretty heavy load. For Prime95 testing we did after we did use an offset of two, because Prime95 is much more stressful. However, it's easy to run Handbrake first to see if the overclock even stands a chance. Blender also has a benchmark, which takes a bit longer than Handbrake, but which should be a heavier load and should be more indicative of overall stability. In the end Prime95 is what you will need to use to get the most out of your CPU
Prime95 has a few different tests you can run. The default test is a blend test, which tests most everything, but isn't going to demolish CPU core instabilities as Small FFTs would. There is some documentation on how to disable AVX use within Prime95 by adding in a string in the local.text file created when the program runs, but from my testing, that method didn't work.
AIDA64 also has a built-in test, and you can choose what you test (core, FPU, etc.) but I would increase the amount of RAM used in that test as the default value is a bit low. AIDA64 is considered a "safe" test by many, as it's not designed to beat your CPU up, but many believe you can't become a man until you get a really good beating. When you run Prime95 keep an eye on temperatures, as you can see I am in the danger zone (80-90C) already with only 1.3v and 5GHz (5.2GHz with -2 AVX offset)
If your CPU is thermal throttling you can use the new TJmax offset setting added to the 9900K, which will allow you to increase throttle point. Some suggest adding 15C, but we think it's a bit unsafe to use this offset to that extent. The good thing about Handbrake is that it spits out an average work encode speed in FPS, so you can gauge if your performance is increasing or not.
Overall, overclocking the 9900K is quite easy, but you should keep in mind that overclocking can degrade your CPU faster than naturally intended, but most enthusiasts would agree with the long lifespan of modern CPUs and the overall feeling of accomplishment make it worth it.
Last updated: Oct 18, 2019 at 06:11 am CDT
- Page 1 [Introduction to Overclocking and The Flow Chart]
- Page 2 [Disclaimer and Before You Begin Overclocking]
- Page 3 [CPU Multipliers and Voltages]
- Page 4 [Power Settings and DRAM Overclocking]
- Page 5 [Intel Max Voltages and Stability Testing]