I am doing some research on LCD monitors, but I couldn't find enough on the connectors since wikipedia gives too much info that I don't need after reading, and some on google just are not direct enough. What I got from wikipedia is that HDMI supports TV and PC, D-Sub is for PC, DVI is for PC only? (all I read is that it can be used for PC), VGA is only for PC?
Which one of them is best for PC and TV or what are the spec that I should focus on while selecting monitors?
What does it mean DVI is most compatible with HDMI?
I am looking for an LCD for PC and TV. I will be using it for my gaming console/ PC gaming as well as watch TV. If it matters, I have an ATI HD5870 graphics card, and the monitors don't have to be the same for eyefinity right?
D-Sub is the type of connector (15pin), it's analog and also refereed to as a VGA Connector hence if you look at resolution standards you'll see VGA at 640x480. It's called this because it was the first stand it was used for and the name stuck.
Also think of DVI as a connector although its technically an interface standard. It comes in two flavors DVI-A (Analog) and DVI-D (Digital). The DVI-A is compatible with VGA and therefore D-sub with an adapter. DVI-D is digital only and cannot be used with an analog source or receiver. The tricky part with DVI is it can transmit both DVI-D and DVI-A together. So some graphics cards will come with an adapter that splits the signals into 2 connectors of DVI-D and D-sub or DVI-A.
HDMI is a new standard and therefore connector. The signal is compatible with DVI-D and you'll hear most people say the difference is HDMI also carries the Audio source. This isn't entirely true (but thinking of it like this will help), just know there are some limitations with version 1.3 with regards to 3D and 120Hz.
I hope these explanations help and I haven't confused you even further.
Regarding your questions there all connectors and will come on a variety of equipment, not just PC or TV. But typically:
D-sub/VGA is for analog PC
DVI is for PC both digital and analog
HDMI is for Media and PC but digital only
HDMI is compatible with DVI-D
the main benefit of using HDMI over DVI-D for your PC is audio comes down the same cable. But if you’re going 120Hz for 3D use DVI-D or HDMI 1.4 (if you can).
So if your connecting your PC to a monitor it can be HDMI, DVI or D-sub, but I'd go with HDMI or DVI-D. If you have an Xbox or something using HDMI and you only have the one port, use the DVI-D and an audio cable for your PC.
Generally speaking it is best to use a digital interface regardless what type of display you are trying to connect to. That means DVI-D or HDMI. D-Sub (or VGA) is an analog connection.
Most current computer monitors will most likely have DVI-D, D-Sub and HDMI. Inexpensive monitors may exclude the HDMI and the DVI-D connections.
HDTVs will have both HDMI and D-Sub. No DVI-D connection.
DVI-D has been around for a while and it only carries video signals. Note: DVI-D can also carry analog signal with the correct adaptor.
HDMI is newer and carries both audio and video signals. Same specifications as DVI-D, but the connection is physically different.
Regarding Eyefinity, the monitors do not have to be the same. I would imagine they should be the resolution though. Addtionally, Eyefinity requires a monitor with a new type of connection called DisplayPort. If DisplayPort is not used then you will not be able to use Eyefinitiy. The possible connection combinations for Eyefinity are as follows: