PowerMac 7500 quick freezes - why?
Jamie McCarthy
decided to upgrade it last month. I bought a Umax 604/150 from one
source and a 512K L2 cache from another, and installed them both. They
worked great and I loved the speed increase.
Then, about two weeks ago, the Mac began having sudden and quick
freezes. If playing a game, the screen freezes and then spends a few
seconds drawing in just one or two frames, very slowly. If typing, the
keyboard goes dead and mouseclicks don't register. The mouse moves in
jitters. After anywhere from one second to twenty seconds, control
seems to return...for a while. Until it does it again.
There's no pattern to how it happens except that I haven't noticed it
in the first few minutes after turning on the computer cold (so it
_might_ be heat-related). It seems to happen in all apps and not be
related to what software is running at the time. It's happened during
bootup, I saw the happy Mac splash screen erased and redrawn
practically line by line, very painful to watch.
At first, of course, I assumed it was the new hardware I'd bought. But
I've taken it out and tried all four combinations. Now I'm back to the
original 601/100 that came with the computer, no L2 cache, and I've
seen it do the mouse-jitters and slow-redraw, though it seems to be
_better_ than it was with the 604/150 and L2 installed.
Could this be a RAM problem? I've got 64 MB: two 16 MB, and four 8 MB
DIMMS.
Could it be SCSI related? Internal drive and CD on the internal bus,
two to three devices on the external bus using my APS drive's
"ActiveDAT" digital bus termination. My external HD has started,
occasionally, refusing to mount at startup (a reboot fixes).
Any other ideas?
--
Jamie McCarthy
ja...@mccarthy.org http://www.holocaust-history.org/
http://jamie.mccarthy.org/ http://www.censorware.org/
Matthew Pritzker
Actually it sounds like your computer is temporarily kicking down to a
much slower clock speed. One relatively simple thing I would suggest is
to reset the PRAM. I once saw a Q605 running at 5MHz b/c the PRAM was
corrupted. You might also try playing with RAM DIMMs. Also check to
see if any of them are loose, and check the ROM DIMM and VRAM DIMMs
also.
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Matthew Pritzker Graduate Research Assistant
mpri...@iucf.indiana.edu IU Physics Dept.