XFX Radeon HD R7850 Core Edition won't enable 3rd monitor

[jekyll-hyde]

Using an Intel Core 2CPU 6400 @ 2.13GHz with 3Gb, Windows 8.1 Pro (64bit), DirectX 11.

Installed an XFX Radeon HD R7850 to enable 3 monitors (mainly for graphics and CAD work and internet). Have 2 x BenQ GW2350H monitors at 1920x1080 using DVI and a 3rd monitor (Acer T230H) connected by HDMI to the same GPU. It will only work if I disable one of the others.

I tried updating drivers etc. Everything is digital (DVI and HDMI). Not using any MDP to (X) adapters.

Any idea why the system will not allow a 3rd monitor to be enabled? Something I have done wrong?

The single 6-pin PCI-E power is connected.

Thanks for any advice you can offer.

 

[jessterman21]

I believe the HDMI is connected to one of the DVI controllers - you have to use DisplayPort for a 3rd monitor.

 

[mauller07]

you need an active displayport to dvi adapter to get the third monitor working. most cards only support 2 legacy outputs at a time so only either 2 dvi-d, 1 dvi-d 1 hdmi, or 1vga and either 1 dvi or hdmi. but not all 3 at once.

for a third monitor you need to use the display port output but it has to be an active adapter which are a bit more expensive, passive adapters just pass through a legacy signal but you have the same situation of only being able to use 2 legacy outputs.

the reason being that most ati cards unless they are older multi monitor cards which tend to be more expensive tend to only come with 2 ramdac's which control the signaling clock for the display outputs.

i think more modern nvidia cards are a bit different and may come with 3 ramdacs as i have seen setups with 2d surround and an auxillary monitor using 2 dvi and a hdmi output for the auxillary on the main card and the third monitor on the secondary card.

 

[jekyll-hyde]

I believe the HDMI is connected to one of the DVI controllers - you have to use DisplayPort for a 3rd monitor.

Thank you so much for responding so quickly!

Ahhh...never thought to try that!

So here is another question then...if I used a MDP (active) adapter on a regular (4:3 @ 17") monitor that has VGA, would this still work too? I just want to get a 3rd monitor onto my PC for my CAD work I do. Borrowed this Acer from work to see if it was a digital vs analog issue.

 

[jekyll-hyde]

you need an active displayport to dvi adapter to get the third monitor working. most cards only support 2 legacy outputs at a time so only either 2 dvi-d, 1 dvi-d 1 hdmi, or 1vga and either 1 dvi or hdmi. but not all 3 at once..

Thanks, mauller07.

Could you possibly suggest some "active" MDP adapters?

I went into a few different stores (a few Mac dealers, Future Shop, Best Buy etc) and they all looked at me like I was on crack - "active adapter??")

Thanks for any assistance. So much appreciated. This has been so frustrating. Cards like this should really change their box info. The XFX says, and I quote "up to 4 displays". No mention of needing anything beyond the necessary cables or adapters.

 

[mauller07]

well it does support up to 4, just 2 have to be using display port outputs.

yes unfortunately most of those places you go to the staff are not tech literate beyond what they are trained.

this should work fine http://www.amazon.com/HIS-HMDPSDVIEYE-Mini-DisplayPort-Adapter-Eyefinity-ready/dp/B004RFGK30/ref=sr_1_11?ie=UTF8&qid=1374603932&sr=8-11&keywords=mini+display+port+active+adapter this should work perfectly fine for your needs. it only supports up to 1920x1200p as it is single link dvi.

dual link mini display port to dvi are rather pricey, the cheapest suprisingly i have found is the apple mini display port to dual dvi adapter (it is active) their normal adapter is only passive.

 

[jekyll-hyde]

well it does support up to 4, just 2 have to be using display port outputs.

this should work fine http://www.amazon.com/HIS-HMDPSDVIEYE-Mini-DisplayPort-Adapter-Eyefinity-ready/dp/B004RFGK30/ref=sr_1_11?ie=UTF8&qid=1374603932&sr=8-11&keywords=mini+display+port+active+adapter this should work perfectly fine for your needs. it only supports up to 1920x1200p as it is single link dvi.

That is awesome, mauller. Thank you so much for the information and advice. I had a feeling it had something to do with the adapters.

Final question...If I purchase an active adapter like the one you suggested, am I able to use a typical DVI to VGA adapter (http://www.creativecomputing.net/images/DVI%20to%20VGA.jpg) on that for the time being? Or should I be looking for an active adapter that is specifically VGA and then get another that is DVI when my monitors change?

 

[mauller07]

if one of your monitors already supports Dvi then it would be better to just get a dvi adapter.

if one is only vga then use the dvi to vga adapter on the dvi-i port on the graphics card and the hdmi output.

better overall to use digital connections.

the displayport adapters only support the output the adapter is made for so you will not get a VGA signal out of the dvi adapter.

 

[jekyll-hyde]

if one of your monitors already supports Dvi then it would be better to just get a dvi adapter.

if one is only vga then use the dvi to vga adapter on the dvi-i port on the graphics card and the hdmi output.

Perfect! Thank you so much again, mauller. Found a chain here that carries all these adapters (in stock too!) so I am on my way now. Appreciate all your help this morning. All the best!!

 

[mauller07]

no worries mate, would be nice to hear back when its all working