For those who are not privileged enough to have a HD ready monitor and even a HD ready graphics card you are usually left with one of two display options; VGA or DVI. VGA (Video Graphics Array) has been around for years and as long as I can remember has always been the standard graphics output for a computer, a few years back DVI (Digital Video Interface) came along and nowadays is becoming a lot more common, in particular a lot of new monitors support both outputs as do newer graphics cards, but what exactly is the difference between the two?

VGA – What most people don’t realise is that VGA is actually based on analog signals, although the images themselves start as digital signals they are converted into analog to send through a VGA cable, they are then converted back to digital once at the other end. Already you can see that this isn’t very efficient and whilst this doesn’t cause a problem with CRT screens (this is because they draw out the image once it arrives by using an electron beam that passes over the coating of the screen inside) it does cause an issue with LCD screens, and let’s face it; you don’t often see CRT monitor nowadays! LCD screens by having fixed pixels, the VGA image display then needs to essentially do an image map that matches up the pixels giving an accurate display. Therefore VGA needs to apply clocking and synchronizing to ensure that the pixel maps match up, and when this is out of sync then image problems occur, things like blurring and ‘banding’ on the screen, giving a poorer overall image quality.

DVI – In comparison, DVI uses an all digital signal to send image information from the graphics card to the monitor; this means no more analog signals that require clocking and synchronizing. In short this means you get a faster, sharper and cleaner image transfer and therefore a better display. The one thing to remember about DVI is that there are three different format types, as follows:

dvi-d

1. DVI-D - These are referred to as 'true digital video' and are the standard connector type between a graphics card and a monitor with DVI output.

dvi-a

2. DVI-A - These are used to connect a DVI graphics card to a VGA analog output, for example on an old CRT monitor. This kind of connection suffers from similar problems that a native VGA connection would.

dvi-i

3. DVI-I - These are cables capable of transmitting either digital to digital, or analog to analog.

In conclusion, DVI cables are the much better choice for video displays that are not capable of HD. Whilst DVI cannot compete with the fantastic image quality of HD, they are still much better than VGA and with most new monitors and graphics cards coming with DVI as standard, there is no reason not to change to DVI!