Review Update Lenovo ThinkPad X1 Carbon Touch 20A7-002DGE Ultrabook

The X1 Carbon has two display options: the entry-level model ships with a TN panel and WXGA resolution (1600 x 900 pixels and 131 dpi - not available in all markets); our review model is equipped with the a touchscreen IPS panel and WQHD resolution (2560 x 1440 pixels, 210 dpi). We already reviewed this particular panel, so this time around, we are just going to check for possible variations within the panel series.

And indeed: with an average brightness of 226 cd/m², the display is darker by yet another 10 % when compared to the previous review model (252 cd/m²), which was not bright enough in our opinion. After all: Lenovo promises 300 cd/m² and the competitors Dell Latitude E7440 (302 cd/m²) and Fujitsus Lifebook U904 (306 cd/m²) are quite a bit brighter. The ThinkPad is suitable for working inside without major restrictions, but outdoor usability definitely suffers as a consequence.

While TN panels react to even smaller head movements with a deteriorating picture quality, displays with IPS technology exhibit a much better viewing angle stability, although differences in quality are noticeable as well: in the vertical plane, angles of above 30 degrees result in a slightly lower brightness and subtle color changes. Some competitors do a better job here, although the display of the review notebook still outperforms any TN panel on the market.Review Samsung ATIV Book 9 Plus 940X3G Ultrabook

The base frequency of only 1.5 GHz of the Core i7-4550U might cause some raised eyebrows at first - after all, even the less expensive Core i5-4200U has a clock speed that is higher by 100 MHz. The Turbo levels of 2.7 GHz (both cores) and 3.0 GHz (single core) of the i7-4550U are comparable to the family member Core i7-4500U, however. The only difference between the two: while the 4500U ships with the integrated HD Graphics 4400, the 4550U comes equipped with the faster HD Graphics 5000. The higher maximum power consumption of the graphics card is responsible for the difference in the base frequency of the CPU section. Like all Haswell processors, the i7-4550U is manufactured using a 22 nm process. The ULV CPU is designed with a TDP of only 15 watts.

One of the main reasons for the very high sticker price of our configuration is the SSD, which features a capacity of 512 GB and uses the modern M.2 interface (SATA 6.0 Gbps). Also noteworthy are the 8 GB of system RAM, which is sufficiently large: since the RAM is soldered onto the motherboard, a later expansion is not possible.

In order for current-generation processors to develop their full power potential, the Turbo has to reach maximum levels - something theReview Lenovo ThinkPad X1 Carbon Touch 20A8-003UGE Ultrabook X1 we reviewed previously had issues with. It seems that Lenovo was able to correct the problem: the Core i7-4550U is now able to reach its maximum clock speed. During single-threaded benchmarks like SuperPi, the CPU reaches the maximum of 3.0 GHz and is able to maintain it. Multi-threaded tests, like the Cinebench R15, the processor handles at 2.7 GHz initially; after about 30 seconds, the clock speed drops to 2.5 GHz in order to maintain the TDP. The notebook behaves identically when running on battery.

The performance of the i7-4550U is equivalent to the already mentioned i7-4500U, so the lower core frequency is not a reason for concern. Notebooks this size don't really offer higher performance, as the following comparison shows.

Lenovo designed the X1 to be as light as possible and uses compact M.2 SSDs for that reason. Our review model ships with the Samsung MZNTD512HAGL, which appears to be a modified Samsung PM841 adapted for the mSATA interface. The transfer protocol is the normal SATA standard with speeds up to 6 GB/s, which means that the new form factor does not offer a performance benefit (note that M.2 drives can also interface using PCI Express technology - but only very few models make use of it)

Our suspicion that the SSD might be related to the PM841 is confirmed when we take a look at the benchmark results, which are nearly identical to the latter. Sequential read speeds top out at 517 MB/s and are thus approaching the limit of the SATA interface; the write speed (which, unlike for Sandforce-based SSDs, does not depend on the compressibility of the data) is also quite good at 336 MB/s. Although the drive cannot keep up with high-end models like the Samsung SSD 840 Pro as far as the 4K test results are concerned, the overall performance is quite impressive.

How is the HD Graphics 5000 different from the HD Graphics 4400? Both are integrated into current Haswell ULV CPUs, but the HD 5000 has twice as many shader units (40 instead of 20 EUs). Users expecting the 3D performance to increase by the same margin will be disappointed: in many cases, the performance is limited by the RAM interface and the HD 4400 quite frequently maintains a higher clock speed - a function of the lower ALU-number in conjunction with the same TDP-rating.

The net result is that the HD 5000 - depending on the benchmark - only has a marginal advantage as far as its performance is concerned. For the 3DMark Fire Strike test, for example, the X1 Carbon performs on par with the fastest HD 4400-class notebooks; for the CAD benchmark SPECviewperf 11, the HD 5000 is about 15 - 20 % faster. Those needing to use construction software like Catia are better off with a professional GPU like the AMD FirePro M4100, which, thanks largely to an optimized driver, is faster by a factor of 6.

The Intel GPU is of course suited very well for normal office and multimedia tasks and even 4K videos play smoothly and with low CPU utilization. Other useful features of the integrated graphics are the very efficient Quick Sync Transcoder or the OpenCL support (for example used to accelerate various filters in Photoshop).

The HD Graphics 5000 handles current games only at lower settings, but for some games (Metro: Last Light, Company of Heroes 2) even the lowest settings don't guarantee acceptable frame rates. Older and less GPU-intensive titles are playable at higher settings, although even Fifa 14, which is known to not be demanding at all, can't be played at the native resolution of 2560 x 1440 pixels. Full-HD interpolation, on the other hand, offers very good quality.

Even though the fan isn't very active for most of the time, the notebook doesn't get overly hot. During idle, we saw temperatures from 25 to 32 °C, under full load (Prime95 and FurMark) we recorded a maximum of 40 °C. The highest temperatures are restricted to the areas around the CPU location and next to the fan exhaust, however, and many parts of the chassis barely get lukewarm. Using the Ultrabook on the lap is possible without any restrictions.

Unfortunately, the Core i7-4550U is subjected to throttling in high-power scenarios. Lenovo is not at fault here, however: it is the low TDP that causes the CPU frequency to drop down to 800 MHz in some cases. The GPU consumes a lot of the available power and, with a frequency of 450 MHz, still makes uses of the Turbo to a certain extent (range is from 200 to 1100 MHz). There is no reason for concern as far as the possible temperature development during the height of summer is concerned: Intel designed the Core i7 for temperatures up to 100 °C - and during our stress test with Prime95 and FurMark, the CPU didn't really surpass 70 °C.