Lenovo ThinkPad T450s Ultrabook Review

Although the screen is identical to the model in our first review sample (LG LP140WF3-SPD1), we re-assessed the brightness and contrast to determine possible production fluctuations. Our new sample now reaches rates of 281 cd/m² and 1007:1 rather than 268 cd/m² and 1110:1 - these minor tolerances can be viewed as normal. Therefore, the quality of the Full HD IPS screen that Lenovo has selected belongs categorically to the premium range, and scores with a decent color reproduction, extremely generous viewing angles, and unrestricted outdoor suitability. Again, we would refer to our previous test report for further details.

The Core i5-5200U is a member of Intel's latest 14-nanometer "Broadwell" generation. It features two CPU cores with Hyperthreading, which clock at 2.2 to 2.7 GHz (2 cores: 2.5 GHz). Therefore, their maximum frequency is approximately 15% lower than that of the Core i7-5600U, which also has a slightly larger L3 cache of 4 rather than 3 MB. Being ULV models, both are specified with a TDP of 15 watts, although the Core i5 will probably be somewhat more energy efficient in practice due to its lower clock rates.

The HD Graphics 5500 processor-integrated graphics core in our review sample is only enabled for basic office and multimedia purposes. The dedicated GeForce 940M takes care of more sophisticated 3D calculations. Graphics switching is automatic - Nvidia's Optimus technology automatically enables the suitable graphics unit, which usually functions quite reliably. Naturally it is possible to intervene manually, and assign single programs (or all applications globally) to a specified GPU.

Disregarding the utilization of expensive 16 GB modules, our review sample already has the maximum memory configuration of 12 GB of RAM (4 GB on-board, 8 GB inserted). A somewhat aggravating limitation - rivals such as the EliteBook 840 G2 can be upgraded by up to 16 GB thanks to two DIMM slots. At least the T450s has an empty M.2 slot in case the capacity of the 256 GB, 2.5-inch SSD is exhausted at some point.

Thanks to the ideal utilization of the Turbo Boost headroom (in both AC and battery mode), the Core i5-5200U  achieves exactly the performance level we had predicted. It only lags behind the considerably more expensive Core i7-5600U by about 15%. Lenovo also has alternative configurations with a Core i5-5300U in their lineup, which in terms of price and performance are positioned roughly between these two models.

Owners of the former T440s model  considering upgrading to the latest T450s should be prepared for marginal performance gains of 10 to 20%. In some cases, the even older ThinkPad T430s is faster because the manufacturer had installed standard voltage CPUs from the 35-watt category. This highlights the trend that has been changing the entire laptop world for some years - new devices are not getting stronger, but increasingly more compact, economic and enduring.

The 2.5-inch SSD in our review sample is not from Intel but from the storage device giant Samsung. The PM871 is a relatively new OEM model that is closely related to the consumer drives of the 850 Evo series. Consequently, the PM871 is also based on stacked 3D NAND cells that provide advantages over the previous, planar TLC flash in both reliability and speed.

Apart from a minor weakness in sequential write - the PM871 apparently has been slowed down compared to the 850 Evo (perhaps for efficiency reasons) - the SSD shows its best side in our benchmarks and is one of the fastest models currently on the market. However, it cannot be completely ruled out that Lenovo relies on several suppliers and installed 256 GB SSDs from other manufacturers.

Nvidia's GeForce 940M is based on the same GM108 Maxwell chip as the older GeForce 840M. Therefore, the technical specifications - 384 Shader units, 24 TMUs, 64-bit memory interface - have not changed; the manufacturer has only marginally increased the base and boost frequencies.

Lenovo clocks the GeForce 940M quite conservatively, and completely omits the Boost mode beyond that. We deem the 1 GB DDR3 memory (2000 MHz effective clock) to be quite low. For example, this limit is soon reached when multiple pictures are opened simultaneously in Photoshop.

Nvidia's GPU outperforms the integrated HD Graphics 5500 by a factor of approximately 2, and places itself just before the Radeon R7 M260X that HP has installed in its EliteBook series. On the other hand, the AMD model has the upper hand in professional CAD applications - SPECviewperf 12 recorded almost identical performance for the 940M as for the graphics processor.

Unfortunately, the low noise level has its price: In some places, the casing's temperatures climb to over 50 °C (~122 °F) during full load, and more than 40 °C (~104 °D) on the wrist rest. However, to some extent we can put these extremely high rates into perspective. The tests were performed at an ambient temperature of 23 °C (~73 °F), and FurMark produced an unrealistically high GPU utilization (no TDP limitation of the GeForce 940M). Therefore, in practice the temperatures should normally be considerably lower.

We will continue with our worst-case scenario anyway, and look at the hardware temperatures after performing the stress test for one hour. The processor slowly comes close to its throttling threshold of 95 °C (~203 °F), but can still maintain its maximum clock of 2.4 to 2.5 GHz. Only a slight decrease from 980 to 940 MHz is seen from the graphics chip, which records approximately 85 °C (~185 °F). Overall, Lenovo's temperature management is under control so that no CPU or GPU throttling should occur in real applications.

As in many other ThinkPads, Lenovo's "Power Bridge" system that is comprised of two batteries is used in the t450s. One has a capacity of 24 Wh and is inside the casing. The other can be inserted into the device's rear. The standard model also adds 24 Wh, but the manufacturer also offers larger models with 48 Wh (+30 Euros; ~$33) or 72 Wh (+50 Euros; ~$56). The total power capacity can thus be doubled from 48 up to 96 Wh. However, the latter two batteries also increase both height and weight.

Our 96 Wh review sample achieved twice the runtimes of the 48 Wh configuration, which is probably due to the improved energy saving features of Windows 8.1 (Windows 7 Professional was installed in the first test). Depending on the application scenario, the T450s lasted between 4 and 31 hours away from the outlet - a more than impressive outcome. Runtimes of approximately 11 to 12 hours will still be realistic with a screen brightness of approximately 150 cd/m² and normal load. Recharging took about 4 hours.

Core i5 processor, GeForce GPU, SSD, and IPS screen the perfect configuration of a ThinkPad T450s in our opinion.

Most users will easily dispense with the at best 20% higher performance of the expensive Core i7-5600U - anyone needing that last bit of CPU power, should opt for the T440p from the outset. The GeForce 940M doubles the ThinkPad's 3D performance and does not push the purchase price or the emissions to unreasonable heights.

We also believe that the optional 72 Wh battery is highly recommendable. Practical runtimes of approximately 12 hours quickly compensate for the battery's weight and thickness, especially since short mobile outings can be bridged with the integrated 24 Wh battery. On the other hand, we do not see much sense in buying the 48 Wh battery; it is just as thick, not much lighter and only 20 Euros (~$22) cheaper than the 72 Wh model.

We have already dealt extensively with the other qualities and weaknesses of the laptop in another place - many of the items listed can be transferred to other configurations. Pupils, students and teachers should definitely take one of the many Education models; some configuration features, such as the GeForce graphics, are only offered to this target group.