When connecting up a PC to a monitor, there are 4 main options: VGA, DVI (with all its different versions), HDMI and DisplayPort.
I will talk to you about each of these options and what the pro’s and con’s are of using them. So let’s just dive in head first.
Video Graphics Array (VGA) is the one that you will find on any PC monitor and almost all modern televisions and it was developed by IBM. VGA uses a 15 pin connector and “the maximum resolution claimed for a VGA connector is 2053 x 1536.”
As opposed to most other technologies, VGA transmits analogue signals, which means that electric noise can interfere and disrupt the quality of the image you receive. This is combated with high quality cabling which can block out more noise; generally the thicker the cable, the better. However, would you want to go and spend a large amount of money on a cable for a technology that is disappearing? I didn’t think so.
Another point is that when you plug this into your LCD monitor, the analogue signal must be converted into a digital signal as the panel in the TV is digital. Because the usage of VGA is diminishing as it is replaced with DVI and HDMI etc, the quality of these analogue to digital converters (ADC) is also declining, meaning that the quality of what you see is actually getting worse with newer monitors.
I do not feel the need to say much more on this other than, if you can…don’t use it!
Digital Video Interface (DVI) is one designed to transmit uncompressed digital video. However, it can also be configured to handle analogue as it comes in 3 different modes: DVI-I, DVI-D and DVI-A.
DVI-I (DVI-Integrated) is the more preferable of the collection. It has the pins to allow it to work with both digital and analogue signals – though it transmits in digital – making it extremely versatile. If you look at the picture on the left, you can see it has all of the pins needed for both signal types.
It comes in both single and dual link (see below), and though you will find this connection on any PC monitor, you may want to note that it will probably not be on your TV monitor. In comparison to VGA, you will notice a much sharper image and because of the digital signal – instead of analogue – the cable quality does not matter unless you are using a cable over 4 meters. To convert this cable to HDMI or VGA all you need is an adapter for each end instead a signal converter that most retailers will tell you to buy.
DVI-D (DVI-Digital) is a digital only DVI cable meaning that there is no support for analogue technologies, like VGA, without a signal converter. Other than that, it is the same as DVI-I; it can be single or dual link and can easily be converted to use HDMI with the use of an adapter.
DVI-A (DVI-Analogue) is an analogue only DVI cable. This is the polar opposite of the DVI-D cable I just mentioned, meaning there is no support for digital technologies without the use of a signal converter. However, it can be converted to VGA easily using a simple adapter.
DVI – Single and Dual Link
In DVI cables that handle digital signals, so DVI-D and DVI-I, there is the option of either single link (SL) or dual link (DL). You can see in both the DVI images that there is an extra 6 pins. These extra pins allow for a higher resolution to be delivered to the monitor by doubling the number of TMDS pairs and hence effectively doubling the bandwidth
When using single link, the DVI specification mandates a maximum pixel clock frequency of 165 MHz. With a single DVI link, the highest supported standard resolution is 2.75 megapixels (including blanking interval) at 60 Hz refresh. For practical purposes, this allows a maximum screen resolution at 60 Hz, for widescreen 16:10 ratio of 2,098 × 1,311 or, for 4:3 ratio, of 1,915 × 1,436 pixels. All display modes that use a pixel clock below 165 MHz, and have at most 24 bits per pixel, are required to use single-link mode.
When using dual link, at a refresh rate of 60Hz you can get a resolution of 2560×1600 and for intense gaming monitors refreshing at 120Hz you can get 1920×1200. All modes that require more than 24 bits per pixel, or 165 MHz pixel clock frequency must use dual-link mode.
Basically, for versatility pick up a DVI-I, it supports high resolutions and is more than enough for what the average PC user will use. I’m a gamer and I use two DVI-I’s for two monitors at 60Hz. DVI kicks VGA’s ass big time as you will see a notable image quality difference just from switching connections.
But read on because these next two options may be more useful for you.
High-Definition Multimedia Interface (HDMI) is the one that pretty much everyone will have heard of as it is a common connector found on TV’s and PC monitors and some graphics cards support it. Though it is similar to DVI, as in the signal is identical, there is not really a use for it in the PC community, this is a connection that is mainly found in home cinema systems and multimedia as it supports 3D video transmission and also carries audio.
DisplayPort comes in one, two and four-link versions with increasing data capacities, currently it can transfer 17.28 Gbit/s. The cable can be found in either copper or fibre optic with maximum lengths of 3 meters and 15 meters respectively.
Unlike HDMI’s 4 cent royalty fee, DisplayPort is completely royalty free, meaning that it costs manufacturers absolutely nothing to implement it which lowers the price we pay for the product – OK yeah, not very much…but still.
DisplayPort was designed from the outset with direct graphics card/monitor connection in mind, so it comes as no surprise to find out that full DisplayPort 1.2 can drive four 1920 x 1200 monitors from one port. Another advantage is that It can run a monitor directly from the DisplayPort signal, with no Low Voltage Differential Signalling (LVDS) circuitry required on the panel and there’s a bi-directional auxiliary channel, which can be used for input from a microphone or USB device with a bit rate of around 720 Mbit/s. Plus the button you can see on the top of the connector is an easy-to-use cable retention system, much nicer than the screws on DVI/VGA and the lack of cable retention on HDMI.
Analogue and Digital Compatability
When I worked in an electronics hardware store, I would be asked by customers on a daily basis where they could find a “HDMI to VGA converter” or something similar. The problem here is that you have two different signal types, one analogue and one digital. In order for these two connections to operate they need to be converted in the middle of the cable. Cables that do this do exist, but the price is usually much, much higher than what you would pay for a normal cable. As well as that, they often only convert in one direction meaning that VGA (analogue) will convert to HDMI (digital) but not the other way. This would mean that you have to make sure that the conversion is in the right direction for the equipment.
So what does all of this mean Jake? What connector should I get?
Well, ultimately here is the way I see it, though I’m sure other people will have their own opinion.
If you’re building a multimedia PC, or doing a home cinema/theater system then HDMI is probably is the best option for you, so long as all of your equipment supports it. However, if it doesn’t, or you are building a PC, use DVI-I. It gives you great flexibility between digital and analogue signals with the use of adapters that are much cheaper than having several different cables.
If you are building a gaming PC, or any high-end PC for that matter, use display port. They are by far the most powerful connections that we have, though I wouldn’t question you if you used dual link DVI. If your graphics card and monitor(s) support it, then it is just as good an option.
Always take note of the signal type, whether it be analogue or digital.
Multimedia – HDMI
PC – DVI-I
High-end PC – DisplayPort (or DVI)