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View Full Version : DVI to DVI, DVI to HDMI no signal [GeForce Go 7900 GTX]


rezier
02-06-08, 06:37 AM
Hi
I have the following problem. I have Sager laptop based on Clevo 57OU with GeForce Go 7900 GTX. I've recently bought Sharp lcd hdtv and tried to connect it to my laptop using DVI/HDMI cabel (10 feet long). My laptop found the hdtv, but... I still couldn't get any picture on my Sharp hdtv. I've tried different settings in NVIDIA Control Panel (single monitor - Sharp as main one, dual view, clone mode, different refresh modes) and none of this worked - no signal and no change on Sharp screen. I've also tried different drivers those from Sager website and from laptopvideo2go.com and tried all of that in Windows Vista too (normally I use Windows XP Professional). I had the same situation connecting my friend's lcd monitor using dvi. It was discovered and any changes I made were only seen on my laptop screen and the other was blank all the time. Fn+F7 just shut off my screen and on the other there wasn't any change.

I used the same DVI/HDMI cabel to connect my old PC with Geforce 3 to Sharp hdtv (as computer monitor - single) and it worked without any problem. I had full 1920x1080p resolution at 60Hz.

I don't know what more I could try (s-video on my laptop works because I once tried to connect my old TV - I got black/white picture but it worked).

I don't want to use d-sub output to connect my laptop to hdtv because I will only get 1024x768 and it's not what I'm wishing for.
Please help!

EciDemon
02-06-08, 07:06 AM
It worked with the GF3 ?
But those dont have dvi right, so im just asuming this signal was analoge (where too long of a cable would result in quallity loss)

Digital dvi is bandwidth limited, unless you got those special cables, about 1meter is maximum length for highres (we use metric so Im not exactly sure how much 10feet is other then it's much more). You cant really get quallity loss with digital signal, it either is or isnt. So I suspect your problem is with your cable.

edit: ok according to cellphone 10 feet is 3meters. Thats too long of a cable Id say

rezier
02-06-08, 07:15 AM
As you see it's pure digital dual link dvi-d http://img520.imageshack.us/img520/3628/leadtekgf3fronthu3.th.jpg (http://img520.imageshack.us/my.php?image=leadtekgf3fronthu3.jpg)

If 3 meters is too long then why did I have perfect picture on my Sharp hdtv when it was connected to GeForce 3 with the same DVI/HDMI cable I've used before? I've seen even 10 meters HDMI cables and mine is a high quality one (golden plated connectors and ferrite filters, very thick).

EciDemon
02-06-08, 07:34 AM
I cant view the image, says i have no premission to do so (forbidden 403)
Dvi cables are a bit confusing, there's a few around, you got dual link cables (doubble bandwidth) single link (would be the one I use, 1m) They can have analoge or not, single and dual just to add to the confusion..

I was just asking as I dont remember Gf3 having dvi thats all. My Gf3Ti200 only got VGA and s-video.

Also keep in mind, lower res requires less bandwidth so you can get away with longer cables, for lets say 1024x768 around 10m would work according to my research.

Edit: I dont know if specs for HDMI cables differs, but asuming Dvi was the weaker link in the chain (all though I presume same rules apply) ...

rezier
02-06-08, 08:00 AM
Cable can't be the problem because:

1) I had 1920x1080p at 60Hz when I connected my Sharp hdtv to GeForce 3 with DVI/HDMI cable

2) I tried connecting my laptop to my friend's LCD monitor and it was discovered but still I had blank screen (just like with Sharp in my first post). My friend is using this dvi/dvi cable (which he got with his LCD monitor) with his PC everyday and he has no problem at all.

EciDemon
02-06-08, 08:15 AM
Thanks for fixing the image :)
This x-mas im also going to decorate my x-mas tree with my old nvidia hardware too :D

Anyways, there's no obvious error in the setup that I can see other then what I already sayd about cable length, and since your friend can use the very same cable on his setup Im all out of answers.
I was thinking maybe signal strength is to blame. If I could id bring my dvi cable with hdmi converter just to make sure.

I dont think it's hardware error in your laptop either so I hope an expert on the matter sees this thread. Im actually very much interested in the matter too as at one point or another Ill get a big flatscreen tv too.
Im sorry I could be of any help

EciDemon
02-06-08, 08:50 AM
Ok, do some searching on Reduced Blanking/CVT-RB or Discrete monitor timing.
Im sure your problem is there and possible solution too (related again to bandwidth)

Problem is, with nVidia controll panel, to my knollage you cant edit resolutions under Vista.

rezier
02-06-08, 09:00 AM
Ok, as for Vista you can be right, but I can't do nothing to be sure of that. Anyhow I just installed Vista to check if this could solve my problem (because i could have accidentally turn off some services or get corrupted drivers under my XP Pro).
Under XP I changed resolutions and refresh rates and I didn't see a single change in Sharp behaviour - it was blank before and after my changes. Only resolution on my laptop has changed.

EciDemon
02-06-08, 09:07 AM
http://www.playtool.com/pages/dvicompat/dvi.html

Check this out, do a page search for "reduced blanking"
Notice the charter where supported resolutions on normal timeings vs reduced blanking you'll see that full HD is out of range on single link dvi cable.

A bit lower in that section there are images that describes how to add new resolutions with reduced blanking enabled for both ati and nvidia (new and old control panel) however, that controlpanel part is missing in Vista drivers to my knollage (in v 171.16 they are defanatly missing, the one im using)

rezier
02-06-08, 10:13 AM
Thx for the link, I've read it all and tried connecting my laptop to my friend's LCD monitor once again (dvi single link cable), I've set reduced blanking but there was no change. I just don't get it... monitor (and Sharp hdtv the same) installs as Plug and play, I can see their names in Nvidia Control Panel (for hdtv its Sharp, and for LCD monitor is P19 with native resolution 1280x1024) but when I change anything it still looks like in standby mode.

EciDemon
02-06-08, 10:39 AM
Dang, then im out of ideas :(

Did you try low res such as 720p etc (1280x720) or even lower such as 800x600, 1024 etc ?

If it was a bandwidth vs cable length issue, in lower res it should work.
I still stand by my statement on 1m single link dvi cable for highres (1680x1050 and up)

Im sure one of the real experts in the matter comes along here with some good pointers that I might have overlooked. The board at this time isnt that active.

rezier
02-06-08, 10:53 AM
I tried even 800x600. I would agree that it could be a bandwidth/length problem, but there is no reaction on screens both of the displays I've tested (Sharp, and LCD 19" Fujitsu monitor) and why the LCD works with native resolution 1280x1024 connected to the with single link dvi-d PC? And Sharp worked perfectly on 3m cable 1920x1080@60Hz connected by dual link dvi/hdmi cable to my old PC with GF3. I guess in the end problem must be somewhere else...

EciDemon
04-09-08, 04:04 AM
edit:sorry accidently bumped an old thread