Dual Monitor with Sapphire RX 480

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Irushian

Commendable
Dec 30, 2016
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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
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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!
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It doesn't detect another display, that's probably because I have to have the second monitor unplugged to get the first one to work as having them both plugged in causes them both to lose signal by the time I get to the windows login screen.
 
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That's how it was on my HD 7870, though since changing to the 480 it's duplicating the screen on to the second monitor. So I see windows booting up on both til they turn off and when I was in BIOS, it was also displaying the same on both monitors.
 
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I would switch ports, if you can. Both cables are plugged into the GPU, right? Not motherboard. Also, it shouldn't duplicate when booting up or in the bios. It should only show on one. So it duplicates BEFORE logging, but after that, it goes blank?
 
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I've tried switching the ports each monitor was plugged into, as well as switching the adaptors that the monitors were connected to, every combination has the same affect.

But aye, as soon as I reach the windows login screen both monitors will say no signal and turn off. I sat in the BIOS screen for over 10 minutes to see if it would do the same but they both remained on. So in short, they both work when in BIOS, they both show the same thing but as soon as it boots up to the windows 10 log in screen they both lose signal and switch off.
 
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That is very strange. I would try to use one monitor to log into Windows, and update the drivers. It's not a monitor issue, because it works with the other GPU.
 
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I've updated the AMD Crimson drivers, after that failed I uninstalled them, and then used the clean up program from AMD to remove any left over files and then installed the latest version again (version 6.12.2).

Unless you meant some other drivers?
 
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I haven't tried safe mode!

I'll shut down and try after this reply and let you know what happens.
 
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I did a couple of tests while I was in safe mode, both monitors were active though they showed the same thing, so monitor B was a duplicate of monitor A. I went into display settings and it wouldn't detect a second monitor so now I'm more confused than ever! Though hopefully this is something you've seen before and know what has happened. The odd thing is that with my other card it was all working perfectly.
 
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Brand new, less than a week old (I had to wait a few days to get another HDMI to VGA adaptor to get the second monitor running).
 
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Reading up on HDMI to VGA say that these are active, not passive.

http://www.ebay.co.uk/itm/HDMI-to-VGA-Video-3-5mm-Jack-Audio-Cable-Converter-Adapter-PC-TV-XBOX-360-1080P/162337434893?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D38661%26meid%3Df3d3296d0f31448890754c46ce554ce3%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D131940630765

So could it be due to using a HDMI to VGA adaptor this time as I used a DVI-I to VGA adapter with the 7870?
 
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My monitor is VGA only, but as you say the RX 480 doesn't support the DVI-I which is why I got another HDMI to VGA adaptor for the card.

I do have a DVI to VGA adaptor on the way though I'm wondering with the current problem, if resolution would have an affect?
 
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With low resolutions I got both monitors working, though the moment I changed one of them to a higher one they both shut off. I did some searching and according to some sites what I have should both be active, and not passive as they have to change a HDMI source to VGA?
 
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They're both using the adaptors, the one that caused it was set to the resolution of 1920x1080, as soon as I did that I got the signal loss. Though I'm running that resolution right now on it with no issue (just with the other monitor unplugged). It does tell me that the recommended resolution is 1024x768 but that is far too big and I had it running at 1920x1080 fine on the HD 7870 anyway.

I can't remember exactly what resolution the other one was running in, I think it was 1600xSomething or around that area (It's currently unplugged now).

It's just odd that as soon as I changed the resolution, it happened. Though everything is the same as when I was running my system with the HD 7870, well except that one of the monitors was running through DVI-I to VGA adaptor instead of HDMI to VGA.

Are we absolutely sure it couldn't be a faulty card?
 
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Okay, I'll wait til my DVI to VGA arrives and try that out. Hopefully it'll have a different result, thank you! =)
 
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No problem, hope it works out.
 
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