Don't let the all-plastic body fool you, because the B540 in no way comes off like a cheap toy. The combination of metallic grey and glossy black help make it a stylish computer. Like the IdeaCentre B310, and unlike the IdeaCentre A720, the computer sits upright on a picture frame-style stand.
The B540 comes with a wireless keyboard and mouse, which connect via a USB receiver that goes in the back. Both respond as they should and are perfectly suitable to everyday tasks such as productivity and web browsing. However, for more demanding tasks, such as serious video gaming and photo editing, you'll find the mouse lacking. There are all kinds of mice out there that will outperform this one.
The connectivity on the back consists of four USB ports (2 x 2.0 and 2 x 3.0), an Ethernet (RJ45) port, an HDMI out (practical for using two monitors) and an antenna input for the TV tuner.
On the left side are two additional USB 2.0 ports, an SD card reader, a headphone jack and a microphone jack. The right edge houses the DVD burner.
The TV tuner is certainly a plus for bedrooms and small apartments, allowing you to watch TV and save shows on the hard drive using Windows Media Center. It's simple to set up and easy to browse through, thanks to a small remote control that comes included. Just remember that the computer has to be turned on in order for the remote to work, as the TV function is directly linked to the PC functions.
The IdeaCentre B540 heats up when you stress the components with processor-intensive programmes—not inordinately so, but it does get hotter than the A720, a 27-inch all-in-one that nonetheless has similar processing power and a more advanced GPU.
Heat readings with the components under stress.
Images captured with a Fluke Ti25 thermal imaging camera.
On the plus side, the B540 makes very little noise (37 dB(A)), no matter what type of task you run. In an otherwise silent room, it's hardly noticeable.
The IdeaCentre B540's headphone output is identical to the A720's. It reproduces sound well, with good dynamics, although the volume isn't especially high.
The volume delivered by the built-in speakers is low, enough for occasional use, but you won't be using them to blast music at a party.
Our Model:The model we were sent for review features an Intel Core i5-3450S processor, 8 GB of RAM, an Nvidia GeForce 615 video card and a 1 TB hard drive (5400 RPM). Whereas the comments above refer to all versions of the Lenovo IdeaCentre B540, the observations below apply to the configuration we tested only, as each model has different specifications. Individual components may also vary depending on the country/region you live in (see inset).
The IdeaCentre B540 comes with a choice of a 10-point multitouch screen or a regular, non-touch enabled display. We tested the non-touch version. This 23-inch Full HD display uses TN technology, and as a result the vertical viewing angles are particularly narrow, especially when looking from below, where the image quickly fades to black, as is common to all screens with TN panels.
When it comes to colour accuracy and contrast the B540 is very similar to the HP Omni 27. The Delta E is 5.2, which falls short of the B310's 3.3. The contrast ratio is around 720:1, which is also well behind the best ratios on the market (the Asus ET2700INTS, for example, has 3,000:1 contrast). Even the non-touchscreen model has a glossy display, so in order to avoid glare you'll want to position yourself somewhere where you don't have a window, lamp or other direct light source behind you.
Lenovo gave this PC an Intel Core i5-3450S CPU to ensure good processing power. The four physical cores allow it to respond quickly to any task, whether the programme you're using has been optimised to distribute the workload to all four cores (as with 3D modelling) or whether it requires raw power (as with mass data archiving).
However, the IdeaCentre B540 could be made even more responsive with a solid-state drive. You can see the difference during startup, which takes nearly 45 seconds to show the Windows desktop and connect via Wi-Fi. But the 1 TB storage capacity is a comfortable amount of memory for storing TV shows recorded with Windows Media Center.
Don't expect to get much out of the GeForce 615 (3DMark06 score: 6052). Even by setting the screen to 1366 x 768 pixels you'll only be able to play smaller games like Call of Duty: Black Ops or FIFA with good detail. And in 1920 x 1080 you won't be doing more than decoding HD videos.
The IdeaCentre B540 isn't a big energy consumer, with 0.6 W in sleep mode, 55 W with the desktop open and 60 W while playing an HD movie. It consumes less than both the HP TouchSmart 520 (another 23-inch all-in-one) and the IdeaCentre B310 (a 21.5-inch all-in-one).