Dual Monitor with Sapphire RX 480

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Irushian

Commendable
Dec 30, 2016
24
0
1,520
Hey guys,

I've recently upgraded from an AMD HD 7870 to the RX 480 (8gb Sapphire edition) and I've had issues getting my monitors working, it'll work absolutely fine with one of the monitors hooked up but when I have them both they claim no signal and turn off.

They're old monitors that only support VGA, so I've got a couple of adaptors for them, with my HD 7870 I had one HDM to VGA and the other DVI-I to VGA and it all worked great, though the RX 480 isn't compatible with my DVI-I so I got myself another HDMI to VGA and the monitors work, though only when one is connected at a time. I can actually get them both on with the RX 480 before windows 10 boots up and that's when they lose signal.

I've tried upgrading my drivers, then totally uninstalling and running the cleanup tool from AMD and reinstalling the latest (6.12.2), I've reset my BIOS etc as well and I've ran out of ideas. The ports at the back of the RX 480 appear to be fine as I've tried switching as well and when only a single monitor is plugged in it works.

The RX 480 apparently consumes less power than my 7870 did, so that shouldn't be an issue either. I figure it might be something to do with windows as they only lose signal when that boots in (to the login screen) but again, I've tried the drivers and now stumped.

Hopefully I've written enough information here and I hope one of you guys can help me, I've almost lost a full day to this and I really want my second monitor back up and running if possible.

Regards,
Steve
 
Solution
The DVI adaptor had no affect and when I did some more research it claimed that a DVI can't be changed to an analog signal unless it's via DVI-I, which made me wonder why on earth they sell them in the first place.

So I gave up and bought another monitor, connected that via the DVI port and kept the other monitor through the hdmi to vga adaptor and everything worked afterwards. So this brings me to the conclusion that because they both went through the hdmi ports that the system was treating them as a single monitor, and thus going to a resolution on one that the other doesn't support causes a signal loss on both. It's the only logical explanation that I can think of.

Thanks for your help on this, Herc08!
The DVI adaptor had no affect and when I did some more research it claimed that a DVI can't be changed to an analog signal unless it's via DVI-I, which made me wonder why on earth they sell them in the first place.

So I gave up and bought another monitor, connected that via the DVI port and kept the other monitor through the hdmi to vga adaptor and everything worked afterwards. So this brings me to the conclusion that because they both went through the hdmi ports that the system was treating them as a single monitor, and thus going to a resolution on one that the other doesn't support causes a signal loss on both. It's the only logical explanation that I can think of.

Thanks for your help on this, Herc08!
 
Solution
I have the same problem with the RX 480. I have 3 monitors. They all run at 1440X900. two of them are the same make and model and are only VGA one is different and can be digital or analog (I have it on digital). The rule of thumb with multiple screens in AMD since Eyefinity is that you can use 2 legacy connections but if you need 3 or more either the connection needs to be a native display port or an active adapter for the display port.

The weird thing that I have is that at the beginning the monitor that gives me the problem was connected to an HDMI to a VGA adapter and worked fine, but at some point it started turning black the rest, even the digital one that's on the DVI port, I changed the other screen that's the same make and model and it works! but if I try to switch the other it will do the same thing. I wonder is I have to remove the card from the slot, to somehow "reset" it. Just my 2 cents.