Using a DVI-RGB video cable

piros

Well-known Member
Hi guys, I want to hook my pc up to my plasma, I can't use HDMI from my graphics card (Radeon 4850) as amp doesn't have any and I've used them all up on my TV.

Am I able to use this cable to hook the PC up to the amp, then the amp to the TV? I'm sure I read somewhere only certain cards can support this but I can't remember!

Thanks in advance :thumbsup:
 

Alphathon

Active Member
That isn't a simple question to answer. It should work on most graphics cards with DVI, but will not work on those with HDMI. There are also potential problems with the RGB end. First, I'll attempt to explain a little about DVI.

Old computers and monitors use VGA connectors, which is an analogue video connector. Modern TVs usually use HDMI, which is a digital video and audio connection. Pretty straight-forward so far. Now DVI is techically not one type of connector, but 3; DVI-A, DVD-D and DVI-I. DVI-A is essentially a VGA cable with a DVI connector. DVI-D is basically the video portion of HDMI with a DVI connector. DVI-I is BOTH. That cable is DVI-A, so will only work with DVI-A (rare as an output and usually only used for converters like this) and DVI-I connectors. There is a good chance that your graphics card has a DVI-I connector, but it is possible that it is DVI-D. If it was supplied with a DVI-VGA adapter dongle or you have used it with one before it's a pretty safe bet that it's DVI-I, so you're good to go at that end. As it's a Radeon 4850 it seems pretty likelly it's DVI-I as a review I saw for it had such adapters bundled.

The other end could also be a problem though. That cable states that it is RGB component; that is each of the connectors represents either the Red Green or Blue part of the video signal, presumably with the sync signal mixed into the green cable. The way VGA and related standards work is that there is a red, green, blue, vertical sync and horizontal sync signals. Now RGB component can be in three forms: RGB + H + V (5 cables), RGB + C-sync* (4 cables) or RGB with C-sync mixed into the green connector (3 cables). Now if your TV or amp has RGB component, it has to be in the correct format (i.e. the right number of cables) or it won't work and you'll need a separator to separate the signals.


*C-sync = composite sync i.e. the horizontal and vertical sync mixed together.

There is another complication though - the component on your TV/amp is FAR more likelly to be YPbPr and not RGB. YPbPr is a far more common type of component video and you'd need a pretty hefty converter to convert between the two.

However, there may be another way - your graphics card can nativelly output a component signal. Check to see if you have a cable like the one below somewhere. It chould have what looks like an s-video connector on the end (it is actually a video-card multi-out), and just plugs into the corresonding port on your graphics card. You will probably have to tell the graphics card to use it, but thats pretty simple.

EDIT: oops, here's the pic:
m2a_component.jpg
 
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piros

Well-known Member
Didn't realise it was that much of a complicated question, so thanks for the explanation!

The card did come with a DVI-VGA dongle (I am actually using it now as I still only have a 19" CRT :eek::p)

I don't think I have that cable lying around, but I suppose I could pick one up to give it a try if you think it will work. Do you think I should just pick up another DVI-VGA converter and run a VGA-VGA cable straight into the TV and then a 3.5mm-stereo phono cable to the amp for the sound? Which would be the best for PQ, as that is pretty much what it boils down to.

Thanks again for the reply :thumbsup:
 

Alphathon

Active Member
I don't think I have that cable lying around, but I suppose I could pick one up to give it a try if you think it will work. Do you think I should just pick up another DVI-VGA converter and run a VGA-VGA cable straight into the TV and then a 3.5mm-stereo phono cable to the amp for the sound? Which would be the best for PQ, as that is pretty much what it boils down to.

Thanks again for the reply :thumbsup:

No problem mate, glad to help.

As for the VGA + 3.5mm that is certainly possible assuming your TV has a VGA-in. In theory it should be roughly equal in terms of PQ, but again, it's not that simple. Most TVs restrict the component input to 1080i, that is, [email protected] interlaced (roughly equivalent to running 30Hz) so in that case VGA would give a better picture. However, a lot of HDTVs also restrict the resolution of the VGA input. You'd have to look into whether or not your TV does that. Of course even if it is, 720p ([email protected]) is generally preferable to 1080i as the interlacing doesn't make for a very sharp picture and also causes flickering. If restricted, the VGA input is likelly to be set to 1360x768 Also, I don't know how readily available those component adapter cables are. If you could post the make/model of your TV we should be able shed a little more light on it.
 
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piros

Well-known Member
No problem mate, glad to help.

As for the VGA + 3.5mm that is certainly possible assuming your TV has a VGA-in. In theory it should be roughly equal in terms of PQ, but again, it's not that simple. Most TVs restrict the component input to 1080i, that is, [email protected] interlaced (roughly equivalent to running 30Hz) so in that case VGA would give a better picture. However, a lot of HDTVs also restrict the resolution of the VGA input. You'd have to look into whether or not your TV does that. Of course even if it is, 720p ([email protected]) is generally preferable to 1080i as the interlacing doesn't make for a very sharp picture and also causes flickering. Also, I don't know how readily available those component adapter cables are. If you could post the make/model of your TV we should be able shed a little more light on it.

The TV is a Panasonic 42PZ70 :) I don't really mind having it downscale to 720p as it will only be for streaming iPlayer/4od etc rather than using it for blu ray/movie playback.
 

Alphathon

Active Member
The TV is a Panasonic 42PZ70 :) I don't really mind having it downscale to 720p as it will only be for streaming iPlayer/4od etc rather than using it for blu ray/movie playback.

Oh, well in that case I would definitelly recommend using VGA. In fact, as you have the VGA cable etc already, I'd hook it up to the TV now and see what happens when you set the resolution to 1920x1080. If it works, then use that. If not, then use whatever lower resolution it will accept. I'd recommend you set it a resolution of 1360x768 or lower initially on your 19" so that you will definitelly get a picture on your TV, then if you don't get a picture at 1080p it'll switch back after 10-15 seconds so you can try another resolution.
 

piros

Well-known Member
Oh, well in that case I would definitelly recommend using VGA. In fact, as you have the VGA cable etc already, I'd hook it up to the TV now and see what happens when you set the resolution to 1920x1080. If it works, then use that. If not, then use whatever lower resolution it will accept. I'd recommend you set it a resolution of 1360x768 or lower initially on your 19" so that you will definitelly get a picture on your TV, then if you don't get a picture at 1080p it'll switch back after 10-15 seconds so you can try another resolution.

Unfortunately the cable isn't long enough so I will have to buy another but I think I will go that route and give it a go, seems the most simplest option out of them all! :eek:

Thanks for your help, will get back to you if there are any problems :smashin:
 

Alphathon

Active Member
Again, no problem. Just post a relpy to this thread if you need any more help. How long of a cable would you need to reach? The reason I ask is that in general VGA isn't designed for long distances, so you'll need quite a good quality cable and possibly a booster if it's sufficiently long. Of course that is also true of Component or any other video cable.
 

piros

Well-known Member
Again, no problem. Just post a relpy to this thread if you need any more help. How long of a cable would you need to reach? The reason I ask is that in general VGA isn't designed for long distances, so you'll need quite a good quality cable and possibly a booster if it's sufficiently long. Of course that is also true of Component or any other video cable.

It's probably going to be around 6metres, is that too long for a cheaper cable? What make would you suggest?
 

Alphathon

Active Member
It's probably going to be around 6metres, is that too long for a cheaper cable? What make would you suggest?

I can't really make any suggestions about brand, but you'll definitelly need a high quality cable. Remember high quality doesn't necessarily meen expensive. Obviously you can't go for a really cheap cable, but you don't have to go for Monster or any other overpriced bullsh*t like that. You might also have to get 2 cables and a coupler for that length as 6m may be hard to come buy.
 

Alphathon

Active Member
Well that'd definitelly work, the question is how much interferance will it give you? The fact that it's sold in lengths up to 25m though is promising. All I can really suggest with regard to which cable to buy (rather than the type) is try it.
 

piros

Well-known Member
Well that'd definitelly work, the question is how much interferance will it give you? The fact that it's sold in lengths up to 25m though is promising. All I can really suggest with regard to which cable to buy (rather than the type) is try it.

Thanks mate, will try it out then :)
 

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