Radeon 4850: Second (2nd) monitor not at 2560x1440 maximum resolution in Win 7 x64

[wammie]

I have an ASUS EAH4850 TOP/HTDI/512M Radeon HD 4850 512MB 256-bit video card running in Windows 7 x64, and I cannot get my second 2560x1440 monitor set to run always at maximum resolution.

This card has two dual-link DVI-I ports. Both monitors are connected via a dual-link DVI-D cable, which are Monoprice Product ID 10489 27" models. The ATI Catalyst software and/or Windows selections only allow 2560x1440 on one monitor (DVI port 1) and 1920x1080 on the second (DVI port 2).

I've swapped monitors between the ports to assure that each monitor is properly functioning and can physically attain the 2560x1440 resolution display. I am using the latest driver for the ATI Radeon HD 4800 series, version 8.970.100.1100, dated 4/29/2013.

Also, it seems that running both monitors simultaneously IS physically possible. I have some 3Planesoft 3D screensavers, which when set to have a duplicated display on both monitors, WILL display the real-time 3D renders at the maximum resolution on both monitors.

I've done extensive searching in the forums and on the Internet and have yet to find something that fixes the 2nd monitor resolution issue. Most (or all) posts describe using one dual-link DVI-D port and some other graphics port, whereas I am using two dual-link ports. I've tried the registry hacks to add 2560x1440 resolution at the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class and HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video locations. I've tried enabling and disabling GPU scaling. I have not yet tried creating a custom EDID, as I don't think that's the issue.

Can anyone help?

 

[VirtualLarry]

Unfortunately, the current HD4850 drivers are neglected "legacy" drivers. I had issues running my VisionTek reference HD4850 512MB single-slot cards, using the ATI DVI-to-HDMI adapter to get HDMI (supposedly including audio) off of one of the DVI-I ports. Well, if I power on my HDTV monitor before the PC, then I get audio. Until I shut off the monitor, or let it go into sleep mode. Then upon waking it up or powering it back on, the card detects it as a DVI-to-HDMI converter, and shuts off the audio. Mind you, these cards came with that adapter in the box, and it was supposed to be fully supported!

So screw AMD, get a better card. One that's actually supported.

 

[Deders]

I think the problem is that the max digital resolution for a 4850 is 2560x1600 (or 4096000 pixels), this includes both monitors if you aren't mirroring. You are trying to get it to display 7372800 pixels.

The analogue output has it's own max resolution of 2048x1536, if this sounds familiar then it may be the resolution your 2nd monitor is displaying at. Can you confirm this?

 

[wammie]

Unfortunately, the current HD4850 drivers are neglected "legacy" drivers. I had issues running my VisionTek reference HD4850 512MB single-slot cards, using the ATI DVI-to-HDMI adapter to get HDMI (supposedly including audio) off of one of the DVI-I ports. Well, if I power on my HDTV monitor before the PC, then I get audio. Until I shut off the monitor, or let it go into sleep mode. Then upon waking it up or powering it back on, the card detects it as a DVI-to-HDMI converter, and shuts off the audio. Mind you, these cards came with that adapter in the box, and it was supposed to be fully supported!

So screw AMD, get a better card. One that's actually supported.

Thanks much for your response. My own card isn't having trouble quite that bad. Perhaps it wasn't clear in my post, but both of my monitors work simultaneously just fine. However, software only allows me to select 2560x1440 maximum resolution for one monitor and 1920x1080 maximum resolution for the other. I am considering buying a new card, but since this one does 95% or better of what I want it to do, I'd be willing to see if I can get more mileage out of it.

 

[wammie]

I think the problem is that the max digital resolution for a 4850 is 2560x1600 (or 4096000 pixels), this includes both monitors if you aren't mirroring. You are trying to get it to display 7372800 pixels.

The analogue output has it's own max resolution of 2048x1536, if this sounds familiar then it may be the resolution your 2nd monitor is displaying at. Can you confirm this?

Thank you for replying! My second monitor is displaying at 1920x1080.

 

[Deders]

You might try experimenting to see if you can get a higher resolution from the analogue D-sub output, it might not be full but it will be close.

 

[NAC]

I'm having the same problem with a 6950 card. In my case, only one DVI port on the card is dual link, the other is single link. Note that you can't tell from the port, I was only able to confirm that by reading the manual.

 

[itsmydamnation]

I'm having the same problem with a 6950 card. In my case, only one DVI port on the card is dual link, the other is single link. Note that you can't tell from the port, I was only able to confirm that by reading the manual.

im 99% sure that the 4XXX and the 5XXX are the same....

 

[wammie]

You might try experimenting to see if you can get a higher resolution from the analogue D-sub output, it might not be full but it will be close.

Thanks for the suggestion. Unfortunately my video card does not have a VGA port. I did, though, try VGA output from a laptop and the monitor was able to display at full resolution.

I'm having the same problem with a 6950 card. In my case, only one DVI port on the card is dual link, the other is single link. Note that you can't tell from the port, I was only able to confirm that by reading the manual.

Thanks! That's probably the case, although I have not seen this documented anywhere for my 4850.

im 99% sure that the 4XXX and the 5XXX are the same....

So then the 5XXX series has one port with single link data too, though from the connector it isn't evident. Thanks for posting!

I would like to use maximum resolution on the second monitor, of course, since I invested the money for it. Guess I'll be shopping for a new card.

Thanks to everyone who replied to this post!

 

[Vesku]

Yellow was electrically single only on this ASUS 4850:

http://www.tomshardware.com/reviews/geforce-gts-radeon,2274-2.html

 

[Deders]

What if you got a dvi-vga adapter, you know that the part of the plug to the side with the cross is purely a vga passthrough? it might be the case that only one of the DVI ports is capable of VGA passthrough but it's worth a try.

 

[wammie]

What if you got a dvi-vga adapter, you know that the part of the plug to the side with the cross is purely a vga passthrough? it might be the case that only one of the DVI ports is capable of VGA passthrough but it's worth a try.

Sorry for the late reply; I haven't had the time to try this until yesterday. Good news: the dvi-vga adapter did work. At first the 2560x1440 setting didn't appear, but then I used the Custom Resolution Utility (CRU.exe) to add it and rebooted.

To my eye the VGA display on the 2nd monitor is just as sharp as the DVI display on the other.

I hope this thread is helpful to others with this same card. Personally, a friend of mine is letting me try a more capable card, and if that works OK in my system I'll replace this one.

Thanks to everyone who submitted suggestions!