LG OLED48CX9LB in the test: The OLED television that wants to be a 120 Hz monitor

The Xbox Series X and Playstation 5 are about to go on sale. Both consoles will support 4K resolutions at a maximum of 120 Hz. This also applies to Nvidia’s Ampere graphics cards, which are slowly finding their way into home PCs. HDMI 2.1 makes this possible.

But what about suitable screens? If we look at traditional manufacturers, we won’t find anything until next year. Perhaps that is one reason why LG is prominently promoting the 48-inch OLED TV 48CX9LB as a display for games. In our test of the OLED TV, we examined whether this promise can be kept. We think: There are many approaches in favor of it. However, there are some flaws, some of which stem from the TV origin of the device.

When we unpack the screen, we immediately notice that a 48-inch television is actually too big for a small desk. As a pure TV for the living room, however, we consider it a little too small. So it’s good that LG also offers the model in 55 to 77 inches – for more money. The built-in power cord and a total of four HDMI 2.1 ports are on the back of the monitor, as well as a network cable (RJ-45) and cable or satellite connection. There are also three USB 2.0 ports and a PCMCIA card slot. Sound systems are connected using a headphone jack or an optical Toslink cable.

It’s a shame that LG doesn’t sell 43-inch versions or even smaller models. We later find out that OLED is in some cases superior to other technologies such as IPS (In-Plane Switching), VA (Vertical Alignment) and TN (Twisted Nematic), especially in games. On the other hand, it is economically understandable if the company does not want to cannibalize its own monitor division with televisions.

For our test we use a Geforce RTX 3070 from Nvidia (test) . The Ampere GPU should be able to handle most games in 4K and at 120 Hz frame rate. Also important: like the LG TV, the GPU supports HDMI 2.1. So we can enjoy the picture in 120 Hz and in native 3840 x 2160 pixels. However, the television also reports a supported resolution of 4,096 x 2,160 pixels, which no longer fully corresponds to the classic 16: 9 format. 120 Hz and 10 bit color depth are possible in both resolutions.

The 48CX9LB can be installed using the supplied rigid stand or a Vesa mount. We think: When viewed from the front, the thin display bezels and the chic design come into their own. The television also stands solidly and firmly on its fairly large base. One point of criticism, however, is the large rear part of the base, which protrudes several centimeters. The result is that we cannot place the gaming monitor replacement completely on the edge of the table. This increases the lack of space on the worktop.

Windows 10 on the TV (Image: Oliver Nickel / Golem.de)

Not quite plug and play

After commissioning, we notice once again how colorful and rich in contrast OLED panels are. The LG monitor is no exception. The high black levels of OLED technology come into their own when watching films and series. We can see that in the Netflix series Altered Carbon, which is filmed quite dark and rich in contrast and accentuates colors through neon-colored elements in cyberpunk style.

However, if we want to use the TV as a monitor, we have to make some settings. The device is therefore not entirely plug and play. First of all, it is important to switch off various automatic color and brightness controls in the TV’s WebOS menu. It is extremely distracting when the image display changes visibly during work.

Even if we switched off functions such as brightness AI, dynamic contrast and the automatic brightness control, our test pattern behaves a bit strange in connection with Windows 10. For example, the display darkens significantly with large, homogeneous white surfaces. Even when we open the start menu, for example, a difference in brightness and color intensity is already noticeable. This always applies when still images are displayed. In games or when watching series, automatic darkening is barely or not at all noticeable.

The OLED TV shines in full brightness, … (Image: Oliver Nickel / Golem.de)

Even after trying things out for a long time, we couldn’t find out why. LG may be installing an automatic burn-in protection that cannot be changed by the people sitting in front of it. This function is built into at least some other LG products.

We can understand the burn-in protection, but still find it a shame that there is no way to switch it off or at least change it without additional tools. A detour is to use the Filmmaker mode instead of the more responsive game mode. This does not seem to use the automatic darkening, presumably in order not to distort colors when creating photos and videos. However, we then lose the advantage of low input latency. The mouse and keyboard controls feel rather spongy there. Fast games are unthinkable for us.

Automatic dimming makes professional display calibration difficult. We could also find the problem in our test when we measured the device for color accuracy and brightness. Setting a fixed individual illumination here is not easy. Instead, we ran the Displaycal software in front of a black background image in order to achieve the highest possible level of illumination.

The brightness of the panel is sufficiently good, if not outstanding. OLED is really convincing, especially in games.