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What cable to connect an HDMI/VGA monitor to DisplayPort at graphics card?


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#1 peterk312

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Posted 30 January 2014 - 05:56 PM

I bought a used HP xw4600 system (being shipped) that has what I believe is a Nvidia Quadro FX 580 PCIe graphics card in it (seller didn't know specific model, but it came with the original system). Inside the manual for the xw4600  http://h18000.www1.hp.com/products/quickspecs/12792_na/12792_na.PDF the specs for this graphics card indicate:

 

"Connectors:
* 2 DisplayPort, 1 Dual-Link DVI-I.

Maximum Resolution:
* Two DisplayPort outputs drive two digital displays up to 2560 x 1600
* One dual-link DVI-I output drives one digital display at resolutions up to 2560 x 1600 @ 60Hz or one analog display at resolutions up to 2048 x 1536 @ 85Hz

NOTE: This card supports up to two displays."

 

 

I need to run two monitors. One can be connected to the DVI-I, with a DVI to HDMI cable, but the second monitor, which has both an HDMI and a VGA input, has to rely on one of the DisplayPort connectors. I thought that I could use a male-DisplayPort to male-HDMI cable to do this, but I'm running into some confusion about the DisplayPort interface.

In general, I thought it is possible to use the cable above if you go from a DisplayPort OUTPUT to an HDMI INPUT (the reverse does not work), but Wiki says this about DisplayPort:   

"The DisplayPort signal is not compatible with DVI or HDMI. However, Dual-Mode DisplayPorts [or DP++ ] are designed to transmit a single-link DVI or HDMI 1.2/1.4 protocol across the interface through the use of an external passive adapter that selects the desired signal and converts the electrical signaling from LVDS to TMDS. Analog VGA and dual-link DVI require powered active adapters to convert the protocol and signal levels, and do not rely on Dual-Mode. VGA adapters are powered by the DisplayPort connector, while dual-link DVI adapters may rely on an external power source." http://en.wikipedia.org/wiki/DisplayPort

The above suggests that if you do not have a "Dual-Mode DisplayPort" you won't be able to use the male-HDMI connector cable. I know there's an active converter box of some kind for DisplayPort, but I'm not sure that's the only way I can go. I don't want to waste time and money ordering the wrong cable. I can't find any specs on the graphics card that indicate if it has "Dual-Mode DisplayPorts."

Anyone have experience with this?
 


Edited by peterk312, 31 January 2014 - 06:26 AM.


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#2 peterk312

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Posted 30 January 2014 - 06:22 PM

In this manual http://h18000.www1.hp.com/products/quickspecs/13111_div/13111_div.PDF on page 2, aren't they listing that the XW4600 system is compatible for the passive DisplayPort to HDMI adapter cable that HP sells?


Edited by peterk312, 30 January 2014 - 06:22 PM.


#3 Sneakycyber

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Posted 30 January 2014 - 06:41 PM

You should be able to use a standard Display port to HDMI adapter/cable, the difference between the display port ++ is "Full" transmission of Dvi signals including the Audio. With the exclusion of the Radeon HD 7700(or Eyefinity cards) when displaying 3 monitors it requires an active converter. See this


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#4 peterk312

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Posted 30 January 2014 - 10:40 PM

You should be able to use a standard Display port to HDMI adapter/cable, the difference between the display port ++ is "Full" transmission of Dvi signals including the Audio. With the exclusion of the Radeon HD 7700(or Eyefinity cards) when displaying 3 monitors it requires an active converter. See this

Thanks for trying to help.

 

Lots of unorganized thinking in the forum at the link. I guess the most valuable info there is in the first post, but he's mostly trying to distinguish for people what is a "passive" connection and what is an "active" connection. It's just not clear when exactly do you need the active adapter for DisplayPort. People are claiming that if you have three connections, two can be connected through a "passive" cable and if you want the third it has to be with an active converter cable. That might not apply to my specific graphics card because HP specs indicate "this card supports up to two displays." My question is with what kind of cable for the DisplayPort if your monitor uses HDMI or VGA (it's not mentioned by HP)?

Much of that thread is about people looking for ACTIVE connectors for DisplayPort because they want to run THREE monitors. I only need two, and neither needs to have the kind of resolution that dual-link DVI provides. But that's where the problem of DP++ comes in. If your card doesn't support DP++. do you only get lower resolution using a passive connection or does it not function because DisplayPort that is not DP++ certified is not compatible with HDMI? Info at the Wiki link suggests there's no compatibility unless you've got DP++.

I was ultimately hoping I would not have to buy the wrong cables. I thought there was a way to know for sure if a cable will work. I can't get details from HP on the graphics cards they were offering. I can't call HP support because I have no system yet to give them a serial number. I did find this http://h18000.www1.hp.com/products/quickspecs/13111_div/13111_div.PDF which on page 2 has the xw4600 workstation on a list of compatible systems that can use their HDMI to DisplayPort adapter. Is it passive or active (they don't say)?
 


Edited by peterk312, 31 January 2014 - 05:27 AM.


#5 peterk312

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Posted 31 January 2014 - 06:25 AM

From HP in 2010:
 http://h20331.www2.hp.com/hpsub/downloads/HP-DisplayPort-setup.pdf

"What’s the best way to setup a dual-monitor configuration when I have a mix of DVI and DisplayPort outputs?
On graphics cards with both DVI and DisplayPort outputs, if the DVI connection is active it will always be the default display. It is usually more straightforward to configure the display attached to the DVI output first, and then configure DisplayPort displays after this has
been completed. Most currently shipping graphics cards have three outputs, any two of which may be used to create a multiple display setup. For information on what cables and adapters are needed for a variety of DisplayPort configurations, including a mix of
DisplayPort, DVI, and VGA monitors, see the DisplayPort Configuration Mini White Paper."

DisplayPort Configuration Mini White Paper (2009):
http://h20331.www2.hp.com/hpsub/downloads/DisplayPort_Configs_MWP.pdf

Here, the Quadro FX 580 is listed as one of their Nvidia 3D graphics cards. In the fine print it says: "Each graphics card can support a maximum of 2 displays, except for the NVIDIA Quadro NVS 450 which supports 4." HDMI monitor connections are not listed anywhere.


However, if you see this 2009 HP white paper:
http://h20331.www2.hp.com/hpsub/downloads/DisplayPort_Setup_MWP.pdf

They list the adapters sold by HP for DisplayPort that come with their graphics cards. For DisplayPort to DVI it says "uses dual-mode capability of DisplayPort output." This means the Displayport must be DP++ certified, and it likely is a passive connection adapter. In contrast, to do DisplayPort to either DVI Dual-Link (not to be confused with dual-mode) or Displayport to VGA the adapter is listed as an "active device." The question remains though if DisplayPort to DVI (passive adapter) is interchangeable with DisplayPort to HDMI. The only clue I have is this: "Displays with HDMI inputs can be used with a non-HP DisplayPort to HDMI adapter." Again, no mention of is the adapter for HDMI passive or active. You'd assume it can be passive because the DisplayPort to DVI (non dual-link) is likely a passive adapter.

I know it sounds like I'm answering my own question, but I'm not 100% sure. I think I have no choice but to risk getting the wrong cable (a passive male-DisplayPort to male-HDMI).



#6 peterk312

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Posted 31 January 2014 - 02:06 PM

Spoke to HP tech. Guy was really unsure about the details of their graphics card. He said it was "two generations old already." He said when he looked at the specs for the Quadro FX 580 the info on the DisplayPort output says nothing about being DP++ (he claimed to know what this means). He said he'd have to assume it is NOT DP++ but the original type, which is just called "DisplayPort."

He said that you can use an ACTIVE adapter in all cases (for DP++ as well as the original DP), and that if it's only the first version of DP and you try to use only a passive cable it will not work. His only recommendation (given how "old" the PC is) is to buy both cables and see which one works.

So now I'm set to waste money on at least one cable.



#7 peterk312

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Posted 31 January 2014 - 04:47 PM

Even more absurd:

 

Why spend $30 for an active adapter cable to go from DisplayPort out to HDMI in when I could just buy a new video card for the same price that doesn't use the DisplayPort interface? Like this:

http://redirect.anandtech.com/r?url=http%3A%2F%2Fwww.newegg.com%2FProduct%2FProduct.aspx%3FItem%3DN82E16814150600&user=u00000687






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