> NewerTech's GURU? What's this? Is it still available?

NewerTech is out of business, but if anyone wants a copy of GURU (GUide to
Ram Upgrades), let me know and I'll make it available via anon ftp.

> >Speed difference is not dramatic (25 and 33 MHz, both can be overclocked
> >a bit using a clock clip); there's also the Centris650, which is almost
> >a Quadra650, but runs at 25 MHz.

You said that the Quadra 650 only has 4 megs. This is important: if it
ONLY has 4 megs on the motherboard, then make sure it's not a Centris 650;
the Centris 650 with 4 megs on the motherboard doesn't come with ethernet,
and the 68040 is really an LC040 with no FPU.

The Quadra 650 with 4 megs does have ethernet and does have the built-in
FPU.

> Does anyone have experience overclocking a Q650? I'm guessing that
> heat wouldn't be a problem as it seem to stay really cool, even under
> heavy load. (Even sitting on top of a 6100!)

Quadra 650s generally have a newer mask 68040 which runs very cool. Every
single 68040 in every single 650, 800, and 605 I've ever had my hands on
runs reliably at 40 MHz, even chips marked as 25 MHz! Older 68040s, such
as in a Quadra 950 or Quadra 700, often run hot and aren't nearly as
overclockable (one Q700 was stable at 30 MHz, but not 33; and the Q950
could only run reliably at 35 MHz, not 40).

For a Quadra 650, just replace the oscillator next to the innermost NuBus
slot with a 20 MHz oscillator and you'll have a 40 MHz Quadra.

> I found a web page about it, but it would be nice to hear if other
> people have had success before I take my Q650 down...
> http://violet.berkeley.edu/%7Eschrier/faq.html

Marc Schrier's site is the definitive place to look.

I've set up probably a dozen overclocked Quadras. Three are Q650 / Q800
running as full time IP NAT machines for cable modems, and are always up
without any problems. Two are 40 MHz Quadra 605s used for building binary
packages for NetBSD. Another Q605 is a backup DNS and sendmail server for
a large organisation.

And they're cheap. Get the Q650 if it's not a Centris. And get the A700,
too, if you can find a use for it! Why not two?

John Klos