Many people felt a bit cheated when they first used their shiny new 3900X CPUs. AMD had marketed them as having up to a 4.6GHz boost clock, but failed to mention that this only applied to single core boosts.
If you try and boost multiple cores at the same time you’ll very quickly find your boost drops significantly, almost to the base clock in some cases.
In this guide I’m going to show you how you can increase the multi-core boost speed of your 3900x and get a bit more performance out of your system.
AMDs 3rd Gen Ryzen processors make use of an awesome free application from AMD called Ryzen Master. If you don’t have it already go and get it now, because it’s the basis for the rest of this guide and a really usefull tool.
I’ll preface the rest of this guide by stating three things:
- The options presented by Ryzen Master like “Auto Overclocking” aren’t particularly useful
- If you’re serious about overclocking a 3900X you should invest in a decent aftermarket cooler to get the best results
- I’m not responsible if you cook your CPU, you do this at your own risk
I’m going to split this guide into two parts, in the first I’ll describe how to get the best performance for multi-threaded workloads and in the second how to get the best gaming performance.
Best Multi-threaded performance
The 3900X comes with 12 physical cores and 24 logical threads, which is great for productivity loads where thread count is important.
But, as described above, if you try and boost all cores at the same time your boost speed will settle significantly lower than advertised.
The problem is the heat generated by the CPU when all cores are boosting, so we need to find a way to reduce the temperatures, allowing the CPU to boost higher without cooking itself.
The first step is to install and then open Ryzen Master, you should see a window like this:
Take a moment to familiarise yourself with the layout. Along the top you can see a bunch of indicators showing you temperature, power use, etc. and a bunch of info further down about clock speeds and the like.
On the left hand pane you’ll see that we’re currently on the Home tab. Click on the “Profile 1” tab and you’ll see the following:
Select “Manual” from the toolbar (top right).
Next scroll down to “CPU Voltage” and change the value from the default to 1.3V. By supplying the processor with less voltage we’re reducing the amount of heat generated in use. But, the tradeoff is that we may introduce instability to the system if we reduce the voltage to a point where signals are no longer transmitted properly:
Next go down to “Memory Control” and click the “Excluded” button so that it changes to “Included” and the options below it become accessible:
Set the slider for “Memory Clock” and “Fabric Clock” to HALF of the speed of your RAM (So if you have DDR4-3200, set the speed to 1600).
Now that we’ve managed the voltage and memory clock speeds the next step is to change the clock speed of the cores on the CPU.
We do this in small incriments, testing after each attempt to ensure stability. My stability test of choice is to use Cinebench R20 on a timed test (File->Preferences->set minimum time to 600 seconds). This will test all cores to 100% for 10 minutes, which should be enough to ensure that the system won’t crash and that temperatures won’t get too high.
You can use the Home page of Ryzen Master to monitor the temperature of your CPU during testing, or you may wish to use HWMonitor which will log the highest temperature of each core during testing.
I would begin by setting each of the cores to 3900MHz and running a test, so set the clock speeds as shown below and click “Apply” at the bottom of the screen:
If your Cinebench timed test works then congratulations; you’ve established a stable overclock!
The next step is to bump up the frequency of all the cores in increments (I suggest 50MHz a time) and running a 10 minute Cinebench test each time. If your system doesn’t crash and the temperature of the CPU stays below around 80 degrees then you should be able to use those settings in daily use.
I managed to overclock my 3900X to 4.3GHz across all cores – a big improvement from the 3.9GHz I achieved out of the box, but still a little short of AMDs claimed 4.6GHz.
In theory you could tinker further using this method; reducing the voltage further may allow for cooler running, and you may have more luck in increasing frequency, it really comes down to the “silicon lottery”!
Best Gaming Performance
I mentioned above that it’s possible to achieve even more performance in gaming.
We achieve this by using the assumption that most games (currently) don’t use more than a few processing cores. This is why Intel is still the gaming king, as they prioritise higher clock speeds over the number of cores in their CPUs.
But, we can use this to our advantage. The 3900X has 12 physical cores, each multithreaded which gives us 24 logical cores. But games don’t need 24 logical cores…..
If we turn OFF multithreading then our system becomes a 12 core / 12 thread system, and this should mean that we generate less heat while running at full speed.
Because of this we can turn our clock speeds up higher and generate less heat than if we were running the CPU with 12 cores / 24 threads.
Within Ryzen Master, click on “Profile 2” – we’re going to use this as our gaming profile.
Locate “Additional Controls” and turn OFF Simultaneous Multithreading:
When you click “Apply” you’ll be asked to reboot, and when Windows reloads you’ll find that your CPU in task manager shows that it only has 12 cores.
You should also notice that the temperature in Ryzen Master is lower than it was previously. This is because multithreading is turned off and the CPU is only using 12 threads, not 24.
From here the process is the same as in the first section; modify the voltage and memory settings and then incrementally increase the clock speed of the cores, making sure that you run a 10 minute Cinebench test in between each run.
You should find that you’re able to hit higher clock speeds than when the CPU had multithreading turned on, which should translate to better performance in games!
Now you have two seperate profiles setup in Ryzen Master – Profile 1 for general use and productivity and Profile 2 for gaming! You just need to switch between the two dependent on what you’re doing and enjoy the best performance from your 3900X!