View Full Version : VGA adapters and performance

02-04-2001, 03:14 PM

Quick question... do VGA sync adapters have a negative effect on video performance?

I ask because of a strange situation I have... I got a PCI Radeon earlier this week, and it wouldn't work at all with my ViewSonic P810 (21")... either distorted video, or complete black screen. It worked fine with my Sony 17sf (17"). Yes, using the new 1.11 driver package.

Just as a shot in the dark, I connected the ViewSonic to the Radeon by putting VGA-->DB25 and DB25-->VGA adapters in between... essentially making a VGA-->VGA adapter (!).

It works!

But I can't help but wonder if it is affecting my vid performance overall. Any thoughts?

(B&W G3/400, great huge heaps of RAM, Mac OS 9.1)

02-04-2001, 03:56 PM
Sounds to me like you have a signal issue and the driver for your Radeon isn't playing nicely with the ViewSOnic. Try restarting without an adapter and changing your sync rates manually either via the monitors CP or the control strip. You can hold down the option key when opening the resolution control strip module to "unlock" all your refresh rates. If you can use an adapter and things work fine, then that would be my assumption. The adapters usually lock in sync and resolution settings, limiting your options. A 21" monitor and the Radeon should give you a heap of monitor settings, which I am guessing aren't available with your adapters plugged in. Try that and see what happens. If you restart and can't see any video (or video distortion) try restarting from the OS CD and it should set it up at 640x480 or something close. Good luck.

02-04-2001, 06:22 PM
There is also a very recent Radeon driver update on out FTP site, however, the monitor should synch even with no driver.

02-04-2001, 09:26 PM
I know that some monitors are particulary finicky. I have a Sun 20" that absolutely will not play nicely unless I have some fairly obscure settings for sync rates. Granted, this is a fixed-sync unit doctored to work on a Mac, but I would assume that a similar issue could occur if there isn't a similar enough sync rate between the Radeon and the Monitor. The adapters try to lock in a standard sync rate and force the components to match it.

The monitor should still sync without a driver....Can you hook up the 17" and select a known-good resolution/sync combo (for the 21"), then shutdown, then restart with the 21" hooked up instead? I know...a lot of suggestions. Let us know if anything works.

[This message has been edited by Dogstarman (edited 04 February 2001).]