HDMI to DVI Problems

[JB200]

I had a PC built with Intel Core 2 Quad-Core Q6600 (2.4 GHz, 1066MHz, 8MB Cache) processor with 4GB RAM. The card is a Matrox QID LP PCIe which supports up to four monitors with resolutions up to 1600 x 1200 each. I am using Windows Vista Business (32 Bit). I want to connect four 37" LCD screens to the system. These screens are LCD TV's made by LG model no. 37LC55 supporting resolutions of up to 1366 x 768. I only want to use 1024 x 768. I am attaching these diplays using DVI (on the PC) to HDMI (on the TV) cables, 5 meters long each. The displays also have a VGA connection.The Matrox card comes with four DVI-D outputs but also has the VGA adaptors.

The problem I am having is that the signal is dropping most of the times as early as the startup of Windows. If I attach more than one monitor the system does not even start. Any ideas where the problem is? Is it the type of connection, length of the cables or is there a problem with the card? Matrox say that the have not tested the DVI to HDMI cables. I am quite surprised as this is probably quite a popular combinition as most PC's have the DVI and almost all LCD TV's come with HDMI. They also say that DVI-DVI should be no more than eight feet if used and the VGA may give better results but still has the same cable length restriction.

The problem is that I need the 5m length as I'll be placing the PC away from the monitors in a commercial premises.

Any ideas??

 

[Psience]

Do you have another video card you can test with? It doesn't necessarily have to support 4 monitors for the purposes of testing. One or two monitor support should be fine since you're trying to test whether your cable length is going to be a problem.

Try something from Nvidia or Ati. As best I can remember Matrox hasn't done much worthwhile in about 5 or 6 years in the way of graphics cards. You may end up having to run 2 video cards to get the results you want.

By the way, DVI and HDMI are supposedly identical in the way they deliver video signal. The only difference is the type of connector they use so you shouldn't have any issues there (HDMI carries sound as well as video though and DVI doesn't). It sounds like you were having a typical tech support experience where the vendor will blame anything but their own product for the problem you're having.

 

[SharpieFiend]

The problem most likely is the cable length - 5m is the maximum for HDMI. At 5m HDMI cables can do all sorts of funky things such as dropping the signal or randomly giving a poor picture, due to resistance in the cable degrading the signal. The solution here is to use native DVI, as that spec calls for a minimum cable length of 5M and it's common (in a good quality cable) for the signal to travel 10m or more. A more expensive solution would be to use a HDMI amplifier, but DVI cables would be much cheaper. I made a post about it in his other thread:

http://www.hardforum.com/showthread.php?t=1274418

 

[xX_Jack_Carver_Xx]

My Westy 42" is connected to my 8800GT with a 25 foot DVI-HDMI cable and works flawlessly at 1920x1080 60hz.

 

[retrorocketz]

These screens are LCD TV's made by LG model no. 37LC55 supporting resolutions of up to 1366 x 768. I only want to use 1024 x 768.

Might be a conflict with the tvs internal scaler, which will scale everything to 1366x768 regardless.

 

[vanilla_guerilla]

its probably the tv's. are the tv's powered up before the pc comes on? try using vga. the difference on a 37" tv at that resolution is not very apparent. the colors look a little more saturated, but thats about it. i am having these kind of problems with my 37" viewsonic and an hdmi cable from a pc. hdmi works fine from the digital cable box, but craps out from the pc. in my case, its probably some hdcp thing. not sure about yours, tho.