TMA - Running 3 monitors off a single graphics card

[Naoru]

So I recently decided to add a third monitor to my gaming rig. Problem is I can't get the third monitor to work with the other two. Google hasn't really been much help.

The card is a http://www.newegg.com/Product/Produc...82E16814102914

Monitors are:

http://www.newegg.com/Product/Produc...82E16824236102

http://www.newegg.com/Product/Produc...82E16824005124

http://www.newegg.com/Product/Produc...82E16824009123

The ASUS is plugged into the HDMI port and the other two are plugged into the DVI ports.

Any help/advice would be greatly appreciated.

[Lana Torrin]

Which video card do you have. NVidia cards prior to the latest gen will only run 2 monitors (even if they have like 5 diferent plugs). ATI cards might need a driver update or somehting (or eyefinity)

Edit: Derp didn't see the link.. What have you tried?

Edit2: OK so Ive had a quick look around.. The Catalist Control Center is aparantly a bitch with this card and you might need to actually turn the port on in there somehow.. I dont know how to do this as I haven't had an ATI card in like 5 years.

[Muffinsrevenger]

Using a 6970 with 3x screens myself, i can't really think of anything obvious, so have some basic troubleshooty!

Is the third screen detected by windows at all?
If you are running the third screen on HDMI, have you selected that as the input source on the screen? Some screens don't auto-cyle between cables but rather stick to the one you chose for it
In the ati control-panel thingy, is the third screen listed under display properties? You know where you can chose resolution etc, are there 2 or 3 available?
Also, ask the catalyst-thingy to run a manual detect for screens, should make no difference but what the hell
If you swap cables around, can you get the "one out" screen to work with dvi? can you get any of the screens to work with hdmi?

[Bombcrater]

You've discovered the big flaw in multi-monitor support on Radeons: three monitors hooked up via DVI/HDMI doesn't work. DVI and HDMI ports both use the TMDS signalling system and Radeons only have two TMDS transmitters shared between all the DVI and HDMI ports on the card, so as soon as you connect a third monitor the card runs out of transmitters and one monitor doesn't work. Even the 78/79xx series cards have this same stupid limitation. VGA is also affected by this because it's on Radeons VGA is generated by a TMDS/VGA converter on the GPU.

The only way to run a third monitor is to connect it to one of the card's DisplayPort sockets via an active DP to HDMI/DVI converter (it has to be an active one, the kind that actually converts DP signals to HDMI/DVI - the cheaper passive kind just route HDMI through the DP socket, which runs you right into the two TMDS transmitter limitation again).

[balistic void]

How is that a flaw in Radeons? It's a flaw in DVI/HDMI coz they were never designed for this.

As others have said: use Displayport or 3 monitors becomes very awkward. It's even more awkward for hires monitors, since you can't even use adapters in that case. Can even get cheap DP monitors these days, the Dell U23xx comes with it and costs about £150. Would not recommend buying a monitor these days without DP.

Additional note about xfire/SLI setups (off topic):
If you have 2 AMD cards in xfire, the outputs on the 2nd card will be DISABLED - so don't count on plugging 3rd monitor into second card (will work fine if xfire disabled).
If you have 2 nvidia cards in SLI, the outputs on both cards are still functional.

[Bombcrater]

I think 'flaw' is a pretty tame word for putting monitor sockets on the cards without enough hardware to make sure they all work. It's nothing whatsoever to do with DVI/HDMI, exactly the same thing would happen to the DP sockets if AMD hadn't included enough controller hardware to run them. (note that NVidia had no trouble making sure their cards can run three DVI/HDMI monitors, even with Kepler being a relatively small GPU).

I'm cynically amused to see AMD 'fixed' the problem on the 78/7900 reference cards by deleting one of the DVI sockets.

[balistic void]

So rather than just adding another timing unit, instead they added a whole new class of socket? If it was easy they would have done it... I don't think either of us is qualified to comment on this tbh.

[Bombcrater]

There's no technical issue here - the GPU doesn't even need to be updated, some board vendors added a seperate third TMDS unit to their custom card designs - just one of bad product planning and a stubborn refusal to put things right. Same goes for the inability of Radeon GPUs to drive any more than two DP ports without extra hardware.

[Naoru]

Bombcrater was correct. Bought an active DP > DVI convertor and it worked first try.

[balistic void]

Couldn't get adapter to work for me with 3x(old) 30" monitors. Couldn't even get two of them to work

Are there 2 types of adapters? The active one has an extra USB jobby for timing right? The fucking adapter I got has dvi+usb on one end, and DP on the other. This is useless coz the old monitors don't have DP >.< Can you get adapters with DP+USB on one end vs DVI-D on other?

Also, OP all your monitors are different sizes. Did you try eyefinity? Is it not a bit shit with mismatched res + sizes?

[Raine Woot]

Couldn't get adapter to work for me with 3x(old) 30" monitors. Couldn't even get two of them to work

Are there 2 types of adapters? The active one has an extra USB jobby for timing right? The fucking adapter I got has dvi+usb on one end, and DP on the other. This is useless coz the old monitors don't have DP >.< Can you get adapters with DP+USB on one end vs DVI-D on other?

Also, OP all your monitors are different sizes. Did you try eyefinity? Is it not a bit shit with mismatched res + sizes?

I could be wrong but isn't the DP end meant to go to the vid card regardless? The point being using your old monitors with the newer vid card's DPs. The USB is probably for power.

[Bombcrater]

Are there 2 types of adapters? The active one has an extra USB jobby for timing right? The fucking adapter I got has dvi+usb on one end, and DP on the other. This is useless coz the old monitors don't have DP >.< Can you get adapters with DP+USB on one end vs DVI-D on other?

The USB connector is there purely for power. Active converters have a chip inside which actually buffers the DVI image data and outputs DP packets, not the most trivial of tasks. Not reversible either, so if the adapter is a DVI>DP one it can't be used to do DP>DVI.

[Liare]

since Naoru got his question answered, mind if i pose another one ?

why are we migrating away from DVI ports ? all i see it offering is a slightly more handy connector and DRM capabilities, the former is negligible in value given the lack of devices that properly support it (most new monitors do, but projectors and what have you ? they have VGA with maybe HDMI, or DVI, or Display port, or a combination) and the latter is hardly something that can be considered a advantage from a users viewpoint, its just more tech added that can and will go wrong while adding nothing worthwhile to the experience.

honestly, VGA is hardly phased out in the real world at this stage, DVI has gained widespread acceptance and now we are getting Display port as well ?

[Mashie Saldana]

DVI is a licensed standard with royalty fees, DisplayPort is free.

[Zekk Pacus]

Mostly it's because DVI is limited to 1920*1200 resolution unless you run dual-link, and 2560*1440 is getting more and more common. Dual link can do it but as I understand has some technical issues.

[Bombcrater]

honestly, VGA is hardly phased out in the real world at this stage, DVI has gained widespread acceptance and now we are getting Display port as well ?

Short answer: chipset level support for VGA and DVI is supposed to be officially phased out by everyone that matters (NV, AMD, Intel and the big OEMs) by 2015. That's not to say either one will go away completely. Graphics card and motherboard vendors will still be able to add a chip that converts DP or HDMI to VGA or DVI, but it'll be a niche thing.

HDMI will hang around for the foreseeable future. It's the standard interface for consumer electronics and that's unlikely to change until you can buy 3840x2160 120Hz TVs cheaply in the supermarket, and even then there's such a huge installed base it'll take 10 years to get rid of HDMI ports. The ease of DVI<>HDMI conversion effectively means DVI hardware will still be usable for a good long time.

Money isn't the issue here. DVI and DP both require no licence fees, while HDMI does. DP is just technically far, far superior. It's scalable to huge bandwidths, one port can drive multiple displays via hubs or daisy-chaining, it's a packet-based interface (like ethernet) that can carry video, audio, ethernet, usb, and other stuff not yet developed over one cable and in both directions. It also has a bunch of power-saving features, like 'partial refresh' - being able to only transmit parts of the image that have changed, rather than always having to send constant stream of whole frames as DVI and HDMI do. DP was also designed to be used internally by laptops, replacing the current LVDS system.

The main impetus for replacing DVI with DP right now is preparation the super-high-res monitors that will come out next year. Dual-link DVI can cope with 2560x1600 @ 60Hz or 1920x1200 @ 120Hz, but DP will be needed for 3840x2160 and beyond.