DVI to HDMI looks terrible compared to VGA

[ZappDogg]

I've got my 8800GTS hooked up to my 1080p Vizio via VGA currently. I tried using a DVI to HDMI cable from monoprice, and the visual quality was noticeably reduced. Colors looked blown out, contrast was terrible, and overscan was an issue.

Any ideas why?

 

[krotchy]

You probably have the aspect ratio settings wrong either in the TV, in the Video card or both. VGA is a computer only spec, so it tends to only come out one way and it will almost always default to no overscan. DVI/HDMI on the other hand is TV and PC so when using a DVI->HDMI cable the computer and TV each make a best guess of what it is getting. Generally the TV assumes 1920x1080 from a computer is going to be 1080p video and it implements a bit of scan by default. You need to make sure that the TV is in Pixel-Pixel mode (or Just Scan, or No-Overscan) or whatever the correct aspect ratio is. On the computer you need to tell it to not scale the image down to prevent over scan. This is somewhere in the Nvidia Control Center but I don't have an Nvidia card in my HTPC so I can't look up where. After that pop a color bar/gradient on the screen and mess with contrast and brightness.

 

[Atomic Playboy]

Could be a few issues. I'd check the following:

Ensure that your television's calibration isn't input dependent. Some monitors will save different settings for brightness/contrast for different inputs (ie. you could have a 50/50 level for VGA, but blow out the contrast and brightness at 75/75 on the HDMI input).
Check your video card drivers and ensure they're up to date. If you're using nVidia, make sure you've set up the monitor profile to "treat as HDTV" and check any color correction settings (also a good idea to check for overscan).
If those don't work, the problem is in the cable. How long a run is it? Are you connecting it to your graphics card DVI port, or are you using a VGA adapter to hook it to your graphics card VGA port? HDMI and DVI are the same technology (though HDMI is capable of carrying audio as well, and obviously has different termination), so there's no reason that you should experience signal degradation when compared to VGA. It could be a bad cable and you may need a replacement.

 

[bovinda]

Aspect ratio problem would be my first guess, too. I had a related issue recently when going to DMI --> HDMI: thread here. Changing the aspect ratio solved all my overscan problems, at least.

 

[rdp6]

Colors were blown out with my macbook pro (DVI->HDMI adapter to HDMI cable to tv) and my samsung lcd tv until I "renamed" the input to 'pc'. I didn't have overscan issues in OS X but did in XP (fixed with a setting in an updated driver). Video is perfect now. Maybe Vizio's tvs work similarly.