Re: [OxLUG] AGP graphics card with decent DVI needed

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Author: Robin Stevens
Date:  
To: Oxfordshire Linux User Group Discussion List
Subject: Re: [OxLUG] AGP graphics card with decent DVI needed
On Sun, Dec 21, 2008 at 09:00:06PM +0000, Philip Armstrong wrote:

> Because any higher & the monitor is unable to sync to the DVI
> signal reliably: there's visual glitches with various colour
> transitions & the monitor will lose sync altogether every second or
> so. It works perfectly with the G4 Powerbook.


This reminds me of a problem encountered when trying to run a G4 Mac
Mini with certain monitors. I'd been happily using one with a 20" Dell
panel (2005WFP) at the native 1680x1050 for some time, so when choosing
a new monitor for my brother to use with his same-generation Mac Mini,
naïvely assumed that there would be no problem with it driving a 20" HP
panel at the same resolution over DVI. He ran into the same problems
you describe, and eventually returned the HP panel and instead picked up
a secondhand Dell 2005WFP, on the grounds that it was already known to
work (even so, he tested it before purchase).

Essentially, there's some timing issue between feebler graphics cards
(such as the Radeon 9200 in G4-based Minis) and *certain* displays that
prevents them being able to drive higher resolutions over DVI. So the
G4 Mini can negotiate a suitable compromise of timings with the Dell
2005WFP, but this isn't necessarily the case with other displays of the
same resolution (as we found with the HP, and with a new 22" Dell).
Trying to find out from the published specifications as to whether two
devices are compatible is nontrivial, as is finding any reliable
technical details as to the exact nature of the timing issues - I'm
afraid I've forgotten the details but may be able to extract some
relevant links from my old mail.

    Robin


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