Dual Monitor on Radeon - 2D Bandwidth Issues?


Oct 29, 2003
I'm currently running dual Samsung 900nf 19" CRTs on a Radeon 9000. I do a lot of Photoshop work so I need the highest resolution possible. Right now I'm running both monitors at 1800 x 1440 x 32bit x 70 Hz. The display quality is phenomenal, but the 2D performance is awful, with really laggy drawing and slow window opening/closing. The behaviour is similar to when your system is really low on RAM, but I have 1.5 GB so that's not the problem.

My question is: Is the crappy 2D performance caused by a lack of bandwidth in the 2D engine of the Radeon 9K or is this something that can be fixed with drivers? I figure I'm pulling 2 x 1800 x 1440 x 4 bytes/pixel x 70 Hz = about 1.38 GB/s out of the 2D core. Has someone experienced similar problems? How do high-end media designers run multi-monitor setups at high res with good 2D performance?

It's probably the ramsinks in this case, and you likely won't do better. Most multi-monitor setups are optimized for 16x12x32 @ 60hz. Anything outside those parameters affects the FPS. How do pros do it. Specialized monitor and specialized cards. Matrox makes the very best, the HR-256, but it will cost you more than your entire rig just for the card. Matrox is also able to squeeze the most out of their RAMDACs giving better performance on the lower speed ones found on the G450 and 550 series than equivalent competition (but now they are equal for those cards) the P650 or P750 MAY give you a boost, but I doubt it would be appreciable at those resolutions.

You may see SOME benifit from increasing the ram of your card (if it's a 64mb version) but even that is unlikely to help you. Even running 1 agp and one pci may do nothing. You are dealing with very high res and good colour depth, so it'll tax most non-professional setups IMO.

I run 1920x1440 on my IBM P260 here at work, but even then I'm forced to run @ 16bit in order to get goof performance. In your case I assume that's not a solution since you want the colour depth. Try running one a low res (your tools/util/file monitor) and the other at the max you desire. That may help somewhat, but even then you may find it maxing out @ 32bit on one monitor, despite what the specs. suggest.

Also what is it (apps) that's causing the hang-ups? Also what proc. are you using?

Anywhooo, Hope that helps.

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