I’m testing a Quadra 950 in the hope of adding it to my collection. But it makes a subtle squeaking noise (not from the speaker), and the internal video becomes distorted when it reads from the hard drive. If I push down the mouse button, for instance, to make a selection in the main menu in finder, it is almost like I can control the squeaking noise. If I use a Nubus graphics card, the video is fine, but the noise persists. On close inspection, the board looks very nice and clean. Has anyone here had a similar problem?
have a look here: http://www.vcfed.org/forum/showthread.php?67996-Levco-SUperMac-Prodigy-SE-accelerator-board-and-utility-software
as well as
Leads on this are pretty cold... it's a SuperMac SpeedCard
Thanks to this eBay seller we know what the driver diskette looks like, and handily the front cover of the manual shows a screenshot of the System 6 control panel, indicating that the cdev is likely just called 'SpeedCard.' Perhaps they or a future buyer could be persuaded to image the diskette.
Other than that, there was mention of one in a collection here in 2007 and another on arstechnica in 2002. It's a long shot, but if you want to track them down it might still pay off...
Edit: One more from 2007, post #14: https://www.bikeforums.net/foo/352410-your-computer.html