Update: This is a “pure CPU” overclocking article, and only looks at CPU performance – gaming tests are done with a dedicated video card. If you are wondering how Kaveri performs when overclocked fully – CPU at 4.7 GHz and GPU at 1020 MHz, check out this Kaveri APU overclocking article.
A little over a week ago, AMD released Kaveri, a new APU architecture that combines pair of dual core Steamroller CPU modules with 8 “Hawaii” based GCN modules for a total of 4 CPU threads and 512 GPU shaders. You can read our full review for more details – today we’ll just be looking at overclocking.
In our Kaveri review, we looked at the top-model A10 7850K, which comes clocked stock at 3.7 GHz base and 4.0 GHz turbo and is fully unlocked. This is actually lower than the prior generation Richland APU which runs at 4.0/4.3 GHz. This might lead you to believe Kaveri to be a weak overclocker, but that wasn’t really the case for us. Using a Noctua NH-U14S and a voltage of around 1.45-1.50v, we were able to get our sample to run at 4.7 GHz. This isn’t just a case of “boot up and take a screenshot of Prime95″ either. This is pretty much rock solid (moreso with one motherboard than the other, but we’ll look at that on a later date).
In our review, we also overclocked the GPU to 1020 MHz – up from 720 MHz – using a NB voltage of 1.2v. This combination led to a pretty big increase in 3DMark Fire Strike.
Since we only had a very short time with the A10 7850K, this was the only overclocking result we had the time to include. Now that we’ve had more time with it, we were able to run our full suite of benchmarks on it, and can now show you the results. We’ll only be looking at CPU results this time around, so we’re comparing Kaveri at stock to Kaveri at 4.7 GHz.
How to Overclock Kaveri
There are many in-depth overclocking guides out there, but we’ll give you a little bit of a quick guide on how to overclock Kaveri using an ASRock A88X Extreme6+ motherboard.
The first thing I found with overclocking Kaveri is that when voltages were set in the motherboard BIOS, it didn’t necessarily ‘keep’ once booted into Windows. This happened on both the ASRock Extreme6+ and Gigabyte G1 Sniper A88X boards I tested with. This could be due to the fact that beta drivers had to be used. Therefore, I would recommend using AMD Overdrive to overclock Kaveri instead. Make sure you are using the latest version, 4.3.1.0690 at least.
You will first need to disable Turbo Core, which allows you to set a permanent clock speed and gives access to CPU VID up to 1.55v. After that, set the voltage to the desired range, hit apply, then apply the desire multiplier. It’s just that easy. Except not really.
To get a proper stable overclock, you are going to have to deal with Vdroop, and that means finding the right Load Line Calibration setting. Vdroop is what happens when the voltage drops under load to try to keep TDP in check. Normally, this is a good thing to keep the CPU running cool and efficient. However when overclocking, Vdroop can lower the voltage to the point where it is no longer stable at the desired clock speed.
Different motherboard manufacturers use different methods to change this setting. Companies like Gigabyte like to use terms like “Extreme” and “Medium” to alter settings. ASRock use a simple percentage mark, with a handy graph showing you how much Vdroop to expect with each setting.
Note that it isn’t as simple as setting it as high as it will go and leaving it at that. Sometimes LLC has the tendency to overcompensate, causing voltage to go higher than desired spec, which can lead to instability or can even damage your CPU. So keep an eye on where the voltage goes while overclocking under load, and adjust the LLC setting accordingly.
After that, disable any power saving settings like Cool n’ Quiet and C6, and you are ready to overclock Kaveri by playing around with different combinations of voltage, load line calibration, and multiplier settings.
By the way, people have asked, and to increase the voltage to overclock the IGP portion of Kaveri, you need to increase the Northbridge voltage. Most motherboards should offer a Northbridge LLC setting as well.