LCD Monitors: What To Look For

About dead pixels

A pixel is an individual module made up of three subpixels -- one each of red, green and blue. A screen's resolution (such as 1280 by 1024) tells you how many horizontal and vertical pixels make up the screen.

Malfunctioning pixels are surprisingly common. They can be stuck in either lit or unlit mode or one of the subpixels can be stuck, which is the most common problem. A dead pixel most likely means you'll see a tiny red, blue, or green dot on your screen. You might think that a dead pixel would be enough to invoke your warranty, but that usually isn't true. Companies have varying policies on how many pixels must be dead or stuck before they will replace your LCD panel. These policies change often, and can vary by monitor model or screen size. Manufacturers' websites should be a good source for up-to-date information, but reviewers say it can be impossible to find. French website BeHardware.com surveyed manufacturers and a major online retailer, publishing results in May 2007. In the short run, manufacturer responses in that report are probably the best source of information, but keep in mind that policies might be different in the U.S. The article also describes the industry standards for dead pixels.

According to BeHardware.com, policies are fairly similar and generally not consumer-friendly. ViewSonic is the only major manufacturer to report that it will, in some cases, replace a monitor with a single dead pixel. You can hedge your bets by going with a company that tries to better the standard, or one that at least has a written policy in place. Many experts say that you may not mind a dead pixel, especially if you have a high-resolution LCD monitor. A free program called Dead Pixel Buddy will let you easily scan your screen for dead pixels. See our Useful Links section for a link.

Here's what experts say to consider when choosing an LCD monitor:

• LCD panel types make a difference. A monitor using VA panel technology is a great choice for business use as it reduces eye strain when working on documents or spreadsheets for long stretches of time. If you have the budget, they are great for multipurpose use as well. A monitor with a TN panel is cheaper. But it's also faster, and therefore best for gaming. TN panels aren't the best, but they are more than satisfactory for most general purpose uses. IPS-based LCD monitors are best for image editing but are very expensive.

• Widescreen displays have weaknesses. Experts say that lighting, brightness and viewing angles on widescreen monitors are often not uniform throughout the display. Reviewers frequently mention distortion around the edges. The technology also introduces video noise. Conventional shapes avoid this problem. Furthermore, experts say that quality declines as size increases with monitors larger than 20 inches.

• For gaming, get a monitor with response-time compensation. A monitor's response time is the speed with which pixels change color, and therefore how quickly the picture can be redrawn. A shorter response time means sharper moving images, which is especially important in games. X-bit Labs says response time compensation makes a big difference in performance.

• Resolution consists of the number of pixels displayed in a horizontal row multiplied by the number of pixels displayed vertically. More pixels means you can see more information on your screen at once. Most monitors allow you to adjust settings to lower resolutions, which can be necessary for people with vision challenges. However, unlike cathode ray tube monitors, LCD monitors usually work best at what's called their "native resolution."

• A monitor's contrast ratio is the difference in light intensity between the brightest white and the deepest black. This specification can help you determine how rich the color will be in on-screen images. Unfortunately, this is another specification without an official standard, so be suspicious of vendor claims.

• The viewing angle is how far you can move to the left or right (or above and below) of the screen's center and still see a satisfactory image. This specification is important if you are using the monitor for presentations, or if more than one person is viewing at a time. It is also more critical for larger monitors. Again, because there's no official standard for this specification, it's best to try out the monitor yourself if this might be a concern.

• Consider adjustability features. Some LCD monitors are height-adjustable. They can tilt forward and back, swivel from side to side, pivot between landscape and portrait views and mount on a wall. These features are critical for some users but unimportant for others. Most individual users will set up the monitor and have no further need for any adjustments. Families with multiple users, however, may prefer a monitor that is easy to adjust.

• Except for entry-level models, most LCD monitors provide both analog and digital (DVI) connectors. While both connectors will generally provide acceptable performance, if you have a video card with a DVI output, DVI may produce a better image.

• Look for a three-year warranty. Although three-year warranties are standard, some manufacturers only provide one-year coverage for some or all models. Manufacturers use warranties as a marketing tool: Longer warranties are often meant to indicate better parts and build quality. A short warranty can be the catch behind a low price.

• Extras like video inputs and USB ports are nice, if you'll use them. Video inputs make it possible to feed a monitor a signal from sources such as a DVD player. A few newer monitors have HDMI inputs.

• Look for Windows Vista compatibility if you plan to watch high-definition movies on your monitor. Vista incorporates a content protection scheme called HDCP, which stands for High-bandwidth Digital Content Protection. Its purpose is to prevent video piracy by encrypting the signal between the source and the display device. If you play a high-definition video from a Blu-ray Disc or a computer file, Vista will first check to make sure your monitor is HDCP-compliant. If it isn't, Vista will reduce the resolution. This is only an issue if you plan to use the monitor to view high-definition movies and other content on a Windows Vista system. Look for monitors with a "Works with Windows Vista" logo on the packaging. Vista imposes no special requirements on monitors for most other purposes. HDCP-compliant monitors will have an HDCP-compliant DVI input or an HDMI input (all HDMI inputs are HDCP compliant).

System compatibility

Be aware that not all monitors are compatible with all computers. Most displays have analog and digital inputs, but some only have analog inputs. Older video cards and computers with integrated video rarely have digital outputs. Some new PCs may lack analog outputs. Therefore, be sure that the monitor you choose has the port you need. Experts disagree about whether a digital connection provides image improvement, but it can prevent interference. Some monitors don't include a digital cable in the box, so you may have to purchase that separately.

Monitors larger than 27 inches require advanced video cards to drive their higher resolution. Manufacturers post compatible video cards on their websites. If you are considering a large LCD monitor and you have an older computer, be sure your graphics card can support the monitor.

A number of LCD monitors are not Macintosh-compatible (though some will work with an adapter). Many monitors that work with both PCs and Macs have limited functionality with Macs.