color fuzz on IIfx, 8*24 card with A/UX 2.0

[Rick Keir, MACC]

We have a number of IIfx machines running A/UX 2.0 in our
computer aided engineering facility.  They are configured
for nfs (if this matters);  they have the 8*24 board and
have NEC brand SIMMs in Bank A;  non-NEC brand SIMMs in
Bank B.  

The ones that have been installed so far share a common problem:
they keep getting fuzzy bars of color on the screen, often 
locking up immediately after.  The color bars resemble the 
problem that MacPaint 1.4 had on the Mac II in 256 color mode;  
that is, it looks like a single-bit deep video picture is being 
stuffed into a video board that is expecting more information.  
However, the bars of fuzz are longer than the old MacPaint bug 
had (that bug produced fuzzy squares;  these are rectangles).

Previously, all of these have had a Mac OS problem where moving 
folders in the Finder would often leave the outline of the folder 
behind, quickly cluttering up the screen with multiple images of 
old folders where they weren't.  On the advice of an Apple 
support tech, we checked for NEC SIMMs in bank *B* of the IIfx 
and found them;  replacing these with non-NEC memory fixed the 
video display problem.  Note that these SIMMs in Bank A don't 
seem to affect the Mac OS at all;  also that at all times these 
machines pass Apple's hardware diagnostics.  Replacing the NEC 
SIMMs in Bank B was done purely on the advice of someone who 
couldn't tell us what it would fix, but that this "fixed other 
things before."  He was right.  

Replacing the Bank A SIMMs is impractical (unless Apple changes 
its tune and takes them back) as we only got the Bank B memory 
replaced by swapping Bank A SIMMs from other machines.

Software config:  CD-ROM distribution of A/UX, installed using 
System 6.05 disks which were copied from shrink-wrapped Apple 
masters and immediately had their write-protect *permanently*
glued in the open position.  NFS installed immediately.  No 
viruses detectable with Disinfectant 2.2.  No non-Apple inits.  
Even removing Apple's inits & drivers (other than the EtherTalk 
and MacTCP drivers) doesn't help.  

*NO* user accounts - the test system we're trying to fix has as
virgin a history as we can manage, and we've even (several times) 
blown away and reinstalled A/UX, in case progressive damage to 
the file system caused by lockups was confusing the issue.

There are supposed to be 12 of these systems in place soon, and 
we can't even get the first few to work.  Any information about 
someone seeing similar problems would help.  Thanks!