DVI to VGA converters

[chang]

My GPU is a Sapphire HD 7870 which has a dual link DVI output aswell as HDMI. I got the chance of a really cheap 1080p 32inch JVC TV at work (?50 cheap) however when I plug it in via HDMI the picture is horrible and just not sharp. The TV has a VGA input so I thought I would just buy one of those convertors. It was a DVI [Female] to VGA [Male] so it plugs in at the tv end of the cable but it wont show a picture.
So the question is would buying the converter so it was at the GPU side of the cable make a difference? The GPU supposedly can transmit digital aswell as analogue through its DVI slot so I'm hoping I dont have to spend loads on getting on of those expensive converters.

Thanks in advance for any advice.

[speedlolita]

Few things to check:

1. Make sure overscan is disabled, or that you have made sure the scaling is 1:1 to the resolution of your display via HDMI. Maybe look up the specs of the screen and match the resolution. I know the ATI software has better scaling options as I used to plug my PC into a sub 1080p screen.

2. Check in your 7870 box, chances are that DVI to VGA adaptor will be sitting in there. DVI carries VGA (unlike HDMI) so using one of those should be no issue with this display if you can't figure out the HDMI options.

[chang]

Thanks for the reply. I cant get my head round the varous options contained within CCC regards using a HD flatpanel. There doesnt appear to be any overscan options within the TV settings. As for the adaptor within the box haha I threw all that away thinking I would never need to worry about using the VGA. Going to take this adaptor back to maplins and get the other one just incase it does make a difference which side of the cable its plugged into....

[briareos_kerensky]

2. Check in your 7870 box, chances are that DVI to VGA adaptor will be sitting in there. DVI carries VGA (unlike HDMI) so using one of those should be no issue with this display if you can't figure out the HDMI options.

DVI carries analog (VGA) only if it's of the I (integrated) or A (analog) variants, although the digital-only variant (D) is very rare. The easiest way to confirm what kind of DVI is, is to read the card specs. 99% it'll be DVI-I.

[speedlolita]

You should be okay setting it to 1280x720 (720p) for now and using the display scaling option in the "My Digital Flat-Panels" option in your Catalyst Control Center.

Don't try use an interlaced signal or it'll look terrible too.

DVI carries analog (VGA) only if it's of the I (integrated) or A (analog) variants, although the digital-only variant (D) is very rare. The easiest way to confirm what kind of DVI is, is to read the card specs. 99% it'll be DVI-I.

You're right of course but in this scenario I simply assumed it was DVI-I as it's a GPU.

[speedlolita]

Whoops.

[fallenangle]

chang should definitely check that the DVI output he's using of his GPU does support VGA too or, as briareos_kerensky indicated, he'd just be wasting his time. However it does look as though it can because it is supposed to have been sold with a specific DVI to VGA adapter. I would suggest that should be used in preference to any third party device.

http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=1160&lid=1&pid=1473

Other makes of the 7870 have different DVI output configurations, some have dual DVI connections, so maybe there are different versons of the Sapphire 7870 card too.

[randombs]

A DVI-VGA cable operates in the same way as the dongle, it's just more or less convenient depending on whether you already have a spare VGA cable lying around. It doesn't do any converting, but you've figured that out already.

As briareos said, you have DVI-D and DVI-I. A graphics card that only does digital over DVI(DVI-D) would not have the four pins for VGA above and below the large flat pin on the right side of the socket(which DVI-I has) so you would be physically unable to connect a dongle or DVI-VGA cable to it:



I've seen monitors that have DVI-D but I've personally not come across any graphics cards with it.

Bearing all that in mind, I think it could be either a settings issue at the PC side or the TV not supporting whatever resolution you're currently set to over VGA. My old Sony LCD wouldn't display 1280x720 over VGA but did over HDMI.

Try this:

Shut down the PC completely and have the TV on the VGA channel. Switch the PC on and see if you get the startup image/text. Graphics cards chat to the TV/monitor when booting up to see what resolutions it can handle.

Also, it should bypass any Windows/CCC settings which may have disabled VGA output(or, possibly, set the DVI/HDMI out as the primary screen).

Or maybe the TV is not an actual 1080p set but will take a 1080p picture and resize it. My current LCD is like that. Its actual resolution is 1366x768 so any other setting looks blurry.

If you can't get VGA working for whatever reason and have to use HDMI:

Over HDMI, is the Windows start button cut off or missing completely? Also, any full-screen programs will have the title and menu bars cut off. If so, that's overscan, which cuts about an inch off each side of the screen and contributes to the blurriness.

There will be an overscan setting on the TV itself but it may not be an actual setting. Sometimes it has a name like JustScan(my Samsung) or 1:1(my LG) and may be just the HDMI input channel without overscan. VGA doesn't have the overscan problem.

[sj33]

Just to emphasise a point above, if you have connected the PC via HDMI running in 1080p and it looks bad, it may be that the TV actually has a native resolution of 1360x768. This is common, my TV is 1080p compatible but is natively actually 1360x768)

Using HDMI, try switching to 1360x768 (note, not 1366x768 as many GPUs cannot output this) and see what happens. If the image looks fine but the sides are cut off, there will likely be a setting on your TV to remove the pverscan (on my TV, it is listed under the screen side setting as 'Full Scan').