Resolution problem with AMD Radeon 5450/6350 and Dell U3011

Johan Mazel johan.mazel at
Tue Oct 30 08:54:26 PDT 2012

I finally found some documentation :
In a short word, for this particular Dell model, Optiplex 990, HD6350
is stuck at 1920x1200. I need to upgrade to HD6450 if I want
This is also the case for Optiplex 960 with an AMD HD 3450 (cf
This means that the guys building graphic card for Dell are
particularly careless/cheap. :/

I'll check the xrandr trick.
I already tried something similar: generating a modeline through
cvt/gft, add it and use xrandr to use it. However, the image was
completely messed up.


2012/10/31 Thomas Lübking <thomas.luebking at>:
> On Dienstag, 30. Oktober 2012 16:14:32 CEST, Johan Mazel wrote:
>> 2012/10/31 Alex Deucher <alexdeucher at>:
>>> On Tue, Oct 30, 2012 at 6:35 AM, Johan Mazel
>>>> Theoretically, the HD5450 is able to display the screen's native
>>>> resolution (2560x1600) according to
>>>> provided that a dual-link DVI cable is used, which is the case.
>>>> Unfortunately, the biggest available resolution is 1600x1200 on Debian
>>>> Testing and 1920x1200 for Ubuntu 12.10.
>>> While the chip is cable of dual link, dual link is only available if
>>> the oem wired up a dual link DVI connector on your card.  If the oem
>>> used a single link DVI connector, you will be limited to single link
>>> DVI.  I suspect that is what's happening.
>>> Alex
>> Are you sure that this would explain both problems (I mean with Debian
>> and Ubuntu) ?
>> One hypothesis might be that the package used by Ubuntu 12.10 fixes
>> the software problem present in Debian's package version while the
>> hardware problems remains...
> Single link is limited to 1600x1200 unless the entire chain supports reduced blanking, what bumps the limit to 1920x1200 (both at 60Hz)
> Support for latter is probably not correctly detected on the Debian system.
> You can use xrandr --newmode and --addmode and see what happens if you try to forcefully select 2560×1600 (but i'd add a "sleep 10; xrandr -s 1920x1200" because the screen will likely turn off - or the DVI link burns ;-)
> Also ensure the cable to actually support DL and is not broken (test on other system)
> Notice that DVI-D does *not* mean "Dual"-Link, but "Digital". You need the pins in the center:
> Cheers,
> Thomas

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