Thermal Throttling and Liquid Metal

Given that the 51nb X210 isn't exactly a polished retail product, we wanted to take an opportunity to perform some hardware and software modifications to see if we could improve the lackluster CPU performance metrics.

First, let's take another look at the baseline performance while encoding a 1080P X264 video in Handbrake.

By monitoring both the CPU frequency and temperature during the duration of the video encode, we can start to see two potential culprits providing a significant performance disadvantage compared to other notebooks with these same processors.

We can see the initial Turbo Boost frequency jump to just under 3.5GHz, which is cut short by reaching the thermal throttling cut off of 100 degrees Celsius. 

However, even when the notebook cools down a bit to just over 80 degrees, the frequency states relatively stable. This behavior points to throttling due to the turbo boost power limit settings.

Given the poor thermal performance and loud fan noise I saw while using the X210, the first thing I wanted to try was replacing the thermal interface material between the CPU and heatsink. Combined with the fact that we've never given liquid metal a try here at PC Perspective, it seemed like a fun experiment.

Armed with our Thermal Grizzly Conductonaut, we disassembled the notebook, eventually gaining access to the CPU and heatsink. Taking the heatsink off, we discovered a quite poor application of thermal paste.

Once the old thermal paste was wiped off, we applied a thin coat of the liquid metal to both the heatsink and CPU die. NOTE: Please research liquid metal and it's limitations before you attempt to do this on any device. Der8auer's video replacing the thermal interface on a Lenovo X1 Carbon was an excellent reference for us, but there are many great explanations of how to apply liquid metal on the internet.

Once the liquid metal was applied and the machine put back together, I ran Handbrake another time to see if any changes occurred. 

Looking at the CPU frequencies and temperatures in the same workload as before, we see not a whole lot of improvement. CPU frequencies remain almost identical, while the temperatures do see a reduction of a few degrees.

Not content with these changes, I installed Intel's Extreme Tuning Utility (XTU) to see if there was any improvement to be gained by undervolting the CPU, as well as adjusting the turbo boost power limits.

After some testing, I found that the highest negative voltage offset I could stably run was -.075.

By undervolting the CPU, we can see sustained frequencies of around 100MHz higher, with temperatures mostly unchanged from the liquid metal only configuration. 

Still not satisfied, I slowly experimented with increasing the Turbo Boost max power limit. Eventually, I settled at a setting of 22W, compared to the stock 15W configuration.

Once more, I ran the same Handbrake workload.

As we can see, we have substantial clock speed increased, putting the X210 at just shy of 3 GHz across the Handbrake workload. However, with higher clock speeds come higher temperatures, with the processor sitting at the thermal throttling limit of 100C for nearly the duration of the 15 minute or so test.

With the notebook in this configuration, I also saw the Cinebench multithreaded score increase to 618, placing the X210 in the top tier of 8th generation notebook processor performance.

This thermal tuning is a delicate balance between a whole bunch of variables on a notebook including battery life, temperature, fan noise, and performance. For instance, an error in the new MacBook Pro's thermal software configuration caused quite the stir in the past week.

Did we perfect the X210? Not by any means. However, I think it's worth noting that XTU will allow you to undervolt and modify the turbo frequencies on many notebooks. For enthusiasts, it's nice to finally have at least a bit of control over notebook performance parameters.

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