R9 280 - how many monitors

[AHarvey]

Hi,

My rig is currently running an MSI Radeon R9 280 Gaming 2072MB DDR5, it has a DVI, a HDMI and two mini dport connections.

I'm currently using the DVI and HDMI to run 2 x 24 inch monitors, but I've another 2 24 inch ones I'd like to setup as well.

Is it just a case of buying 2 mini dport to hdmi cables? is there anything I need to consider?

 

[DrBombcrater]

It's not that easy. On the 280 you can connect only two monitors via any combination of DVI, HDMI, or VGA. Any additional monitors must connect via DP, or an active DP/HDMI or DP/DVI converter unit. Simple adapter cables don't work.

The deeper explanation is this; HDMI, DVI and the DAC unit on the Radeon that generates VGA signals, all use a transmission system called TMDS. The Tahiti GPU on the 280 has only two TMDS transmitters. So if you use the DVI and HDMI ports then you're done, both transmitters are in use. Cheap DP/HDMI cables don't work in that scenario because all they do is tell the graphics card to route HDMI signals over the DP port. Which can't happen as there's no TMDS transmitter available, they're both in use.

So any more monitors need to use the DP ports natively, because the DP protocol doesn't use TMDS, or you need an 'active' converter that takes DP signals from the 280 and converts them to HDMI.

 

[Confused Stu]

Everything DrBombcrater said is correct, but there's yet another twist too!

With the R9 2xx series, AMD introduced the ability to share a TMDS signal between two monitors, but only if they're both timing-identical (for practical purposes, identical make/model) and connected when the PC boots up. This means potentially you can connect third or fourth monitors using DVI/HDMI/VGA without needing Active adapters but only if you don't have more than two different models of screen and they're all attached when you boot up the machine. I personally went with Active adapters when I was running 4 screens from my AMD cards.

Another option could potentially be a DisplayPort Hub from one GPU output, then Active Adapters out to your non-Displayport screens, but at that point there's so many things to go wrong I would definitely go for a different option if it was me.

 

[AHarvey]

Thanks, it confirms what I've read about the card.

Any suggestions on an active converter that will do the job?

2 screens just isn't cutting it anymore

 

[Confused Stu]

I've always gone for Startech adapters personally, simply because their website is very clear and it's very easy to tell from the model number to tell if it's Active or Passive (some adverts aren't clear). However, OcUK actually list a few adapters that sound perfect for you, and they're very reasonably priced:
https://www.overclockers.co.uk/ocuk...ort-to-dvi-d-active-adapter-4k-cb-146-ok.html
https://www.overclockers.co.uk/ocuk-value-mini-display-port-to-hdmi-adapter-4k-cb-144-ok.html

Last time I checked OcUK (a few years back) they only stocked the DP to Dual Link DVI, which was great for above 1920x1200@60Hz, but was £70! Glad they've now got some better priced ones for people with more normal sized screens.

 

[kration]

I've always gone for Startech adapters personally, simply because their website is very clear and it's very easy to tell from the model number to tell if it's Active or Passive (some adverts aren't clear). However, OcUK actually list a few adapters that sound perfect for you, and they're very reasonably priced:
https://www.overclockers.co.uk/ocuk...ort-to-dvi-d-active-adapter-4k-cb-146-ok.html
https://www.overclockers.co.uk/ocuk-value-mini-display-port-to-hdmi-adapter-4k-cb-144-ok.html

Last time I checked OcUK (a few years back) they only stocked the DP to Dual Link DVI, which was great for above 1920x1200@60Hz, but was £70! Glad they've now got some better priced ones for people with more normal sized screens.

+1 for Startech cables. I had similar problems with my 290, and Startech were the only ones that worked reliably.

 

[kration]

+1 for Startech cables. I had similar problems with my 290, and Startech were the only ones that worked reliably.

In fact, see the link to the thread below where I was trying to sort out the problem. Based on subsequent experience, make sure that the connectors to the graphics card are seated very snugly. My set up was very sensitive with very slightly loose or sagging connectors - even a slight tweak/touch would get it working, until they started to sag later...

https://forums.overclockers.co.uk/threads/290-and-eyefinity-which-connectors.18659663/#post-27746596