ThinkPad X1 Carbon Review: Lenovo's 7th Gen Flagship Impresses

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ThinkPad X1 Carbon 7th gen: Battery Life, Acoustics, And Thermals

To test battery life, we used a custom 1080p video running on loop until the system shuts itself down at 5%. Windows 10's Quiet Hours have been enabled to keep any extraneous notifications from stealing precious milliamp-hours of power, too. On each tested system, we calibrated the display to output as close to 115 lux as possible. On the latest ThinkPad X1 Carbon, that actually means  approximately 120 lux, because the next stepping down dropped the display's light output below 100. 

When looking at the results below, bear in mind that the 7th generation ThinkPad X1 Carbon has around a 14% battery size deficit compared to the previous model. Despite the reduced capacity, Lenovo still advertises the X1 Carbon as having "up to" 18.3 hours of battery life. That kind of power-on time probably requires the slower Core i5-8265U processor and a lower-resolution panel. The capacity trade-off drops a bit of weight from the system, but it's not like the last model was all that heavy at 2.5 pounds. Did the change come at the expense of battery runtime? 
chart battery
In a word, yes. The 7th-generation ThinkPad X1 Carbon drops down towards the bottom of our battery life charts. Along with the smaller power pack, the model we tested has to light up a ton more pixels on its 4K HDR display. That resulted in a greater than 25% drop in battery life compared to the previous model, although we still got just over five hours of video playback on a single charge. Dropping the display brightness a bit more would buy some additional battery life if it's necessary. In addition, Lenovo's 1080p or 1440p display options of the new ThinkPad X1 Carbon will undoubtedly offer a bit better battery life as well.

These battery life results are not all bad, though—this Lenovo laptop sits in roughly the same range as other 4K-equipped models, like the XPS 13. Five hours of runtime is still going to get you through a transcontinental flight, and the 65W charger got our test system back to full capacity in just over an hour. In addition, Lenovo's quick-charge technology makes its middling runtime a little more forgivable, though we would have gladly dealt with 0.1 extra pound of weight to have the same 57 watt-hour battery as last year's model. 

ThinkPad X1 Carbon 7th generation Acoustics and Thermals

To test sustained thermal performance, we fired up Cinebench R20. We ran the benchmark twice back to back to see how the system coped with a sustained, heavy load. The results were pretty interesting, to say the least.

first run

Above you'll see the temperatures and clock speeds we observed throughout the first run. While the system would get the Core i7-8665U in our test system up to 3.6 GHz as late as half-way into the run, it settled in at an even 3 GHz and lived with a package temp near a scorching 99 degrees Celsius the entire time. As the clock speeds started to drop, the fan kicked into high gear and was plenty audible. Not pictured but worth noting is that the ThinkPad X1 Carbon is running its Core i7-8665U in "TDP Up" mode, which according to Intel's ARK website, allows the CPU to have a 25-watt TDP rather than the default 15 watts. That lets it run at higher clock speeds for longer, and likely accounts for why the ThinkPad X1 Carbon performs so well in the CPU-bound portion of our test suite. 

As we mentioned during the teardown section, the fan has a little bit of a faint whistling sound to it. It's not always present, thankfully, but once the fans cranked up to full speed, it was always there. It was much quieter than the "whoosh" of air being evacuated from the system, though. Speaking of evacuating air, we could still feel air moving out of the vent eight inches away from the opening, so the fan really does move quite a bit of heat. While those temperatures were quite toasty, the cooling system still allowed the CPU to run at 3 GHz, a full 1.1 GHz above stock, at the end of the run. That's more than 50% faster than the base speed, which is impressive.

Let's take a listen to the system's fan at high speed while this was going on.


Overall the character of the fan has a relatively high pitch, in the 2 kHz range, and there's that hint of whistling above it.  You may also hear a little bit of rumble in the audio, since there's just a little bit of air pushing against the microphone, but you can ignore that. We applied a low-pass filter up to 500 Hz, which stripped out the majority of that rumbling, but otherwise the audio is untouched. 

second run

To see how hard we could push the latest ThinkPad X1 Carbon, we immediately ran Cinebench R20 a second time. Around half-way through the second run, the Lenovo started to drop everything—clock speeds, temperatures and the fan. By the end of the run, the CPU's package temperature had dropped down into the mid-70s Celsius range and the clock speed had dwindled to 2.2 GHz at the very end of the run. As a result, the fan had started spinning down, too. Something other than the CPU—perhaps the voltage regulation circuitry—was keeping the system from running as hard as it did the first time around.

Once we gave the ThinkPad X1 Carbon adequate time to cool down and the fan shut off completely, we restarted the test a third time and the system returned to full speed. That third run completed with the clock speed at a much higher 2.8 GHz, similar to the first run. Overall, the system does its best to maintain high speeds until critical system components need to be cooled down. 

photo noise side

While all of this was going, we measured fan speeds using a sound measurement app on our Samsung Galaxy S10+. In our 30-dB room, the sound meter maxed out at 38.6 dB six inches from the side of the ThinkPad X1 Carbon. In a completely silent room, that slight whistling sound that popped up on occasion could be a little distracting, but for the most part the noise character was more "whoosh" than anything else. 

photo noise front

As we might expect, coming around the front of the unit dropped the noise a little bit, around 2 decibels. Six inches from the front or the side of the machine is a lot closer than you would normally have your ears, and as a result, the ThinkPad is even a bit quieter sitting at the machine normally. 

Next up, we'll recap this deep dive review and render our final verdict. 

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