How can I add a touchscreen to my desktop PC?

http://www.theguardian.com/technology/askjack/2015/apr/16/how-to-add-touchscreen-desktop-pc

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I need to replace my PC setup at home, so your article on buying a new family PC was really great for me. Currently the PC is only used by the children for accessing the web, running Minecraft, iTunes, playing The Sims etc. I would really like to try using a touchscreen monitor to get the best out of Windows 8. I am aware of the argument about gorilla arms, but after using an iPad, I find myself prodding all computer screens with an (unrealistic) expectation that something should happen.

There’s a lot of choice for people who want all-in-ones, but I would much rather get a tower to leave the option of potentially upgrading the PC. I am a developer and might use the family PC for development in the future. Dave

You can add a touch-sensitive screen to any PC – or even an old laptop – by buying a touch-sensitive monitor. There must be a market for them, because most leading monitor suppliers offer them. This includes Acer, AOC, Asus, Dell, HP, Iiyama, LG, Samsung and ViewSonic. The less well-known HannsG also has competitive offerings.

However, touch sensitivity requires extra technology, which is an extra cost, especially for large screens. Touch-sensitive monitors are therefore more expensive than traditional designs, which must restrict the size of the market.

All-in-one or tower?

As you have found, there are lots of all-in-one PCs with touch screens, but they are basically laptop designs with separate keyboards. Slimline designs impose thermal constraints on the processor, which will typically operate at a TDP between 15W and 35W, or less. The processor will be throttled when it gets too hot, and the PC may shut down. By contrast, spacious desktop towers can use processors that run at 45W to 90W or more, so you get more performance for less money.

Towers provide space for adding more memory, ports, faster graphics cards, extra hard drives, optical drives (DVD or Blu-ray) and so on. They are also much easier to repair, so they should last longer. The main drawback is that they take up more space than laptops or all-in-one designs. This may be critical if you want to mount the screen on a wall, which is common with touch-screen PCs used for public information access.

Screen positions

You must consider the flexibility of the design. While the “gorilla arm” argument is simplistic to the point of stupidity – teachers have been using blackboards for centuries – there are important considerations to do with screen distance and angle.

The better all-in-ones provide flexibility to handle different programs and different uses. Often the screen leans back, and in some cases, can be used in a horizontal position. This makes it practical to play electronic versions of family board games, navigate around maps, play a virtual piano, and so on.

Desktop monitors are usually designed to be used with the screen in a vertical position, and relatively high up. This puts the screen a long way from your hands, so you are less likely to use it for touch operations. This contrasts with using a laptop, where the screen may be as handy as the keyboard.

If you decide to go for a touch-screen monitor, choose one that is easy to tilt backwards and possible to use in a horizontal position. Obviously, you should be able to return it to an upright position for word processing and so on.

Alternatively, you can buy any touch screen you like, if you mount it on a monitor arm that enables the screen to be moved around. This may actually be a better option, but it will probably cost more.

Touch-screen considerations

Touch-screen monitors are a bit more complicated than traditional designs, because they are active rather than passive devices. Traditional screens just have to show a picture, whereas touch-screen monitors have to feed information back to the PC. They often do this via a separate USB cable that runs next to the VGA/DVI/HDMI/etc video cable.

Monitors also vary according to the number of touch-sensitive points. This can range from five to 40, but 10 is usual for Windows 8. Further, different monitors may use optical, resistive or capacitative touch technology. Capacitative touch provides the same experience as using a tablet, which is what you want.

Some monitors support a new standard: MHL (Mobile High-definition Link). This enables you to connect a compatible smartphone or tablet to the monitor to show videos with high-resolution sound (up to 7.1 channels, including TrueHD and DTS-HD). The mobile device gets charged while it’s attached.

Other considerations are the usual ones: screen size and resolution, brightness, type of technology (LED, IPS etc), number of ports, whether it includes loudspeakers, and so on. Since you’re a developer, you’ll probably want to knock out a quick spreadsheet to compare all the options.

Note that touch-screen monitors designed for Windows 7 – probably with two touch-points – are less than ideal for Windows 8, where the bezel has to be flush with the display for edge-swipes. However, I don’t expect there are many Windows 7 touch monitors still on the market.

Monitor choice

I have very little experience of different touch-screen monitors, and haven’t tested any, so you will need to do your own research. I can point to some of the products that are available, but unfortunately it may be hard or impossible to see them before you buy one.

PC World, for example, only seems to offer three touch-screen monitors. These are all Acer models with Full HD resolution (1920 x 1080 pixels) and screen sizes of 21.5in (£179.99), 23in (£249.99) and 27in (£379.99). These have MHL support, USB 3.0 and tilt stands that adjust from 80 to 30 degrees, so you could do worse. The 23in IPS-screen Acer T232HLA looks like the best option.

Argos stocks the 23in and 27in Acer monitors, but at higher prices. John Lewis doesn’t appear to stock any.

From my Amazon searches, the ViewSonic TD2220 looks like an economical option at about £180. It’s a 22in Full HD display. However, the 23in HannsG HT231HPB is slightly cheaper (£157.95), and Amazon reviewers give it 4.6 out of 5 stars.

Other touch-screen monitors that might be worth a look include the 23.6in AOC Style i2472P (£262.98), the 21.5in Dell S2240T H6V56 (£207.38) and the 23in Dell S2340T (£339.95). There’s also a ViewSonic TD2340 for £199.99, apparently reduced from £439.99, and a 24in Samsung S24C770TS for £449.99.

I think 22-24in is the optimum size for a Full HD screen, but there are similar options in smaller and larger sizes.

One more thing …

If you have a modern Windows 8 laptop, then you can probably use Windows 8’s touch gestures on its built-in touchpad. In the same vein, you could just buy a touchpad for your desktop PC and use it with a cheaper non-touch screen. Logitech’s rechargeable Touchpad T650 is an expensive option at £114, though the wireless T650 looks a better buy at £39.99.

Have you got a question? Email it to Ask.Jack@theguardian.com