Subject: 6400 bus overclocked
Date: Wednesday, November 7, 2001 2:44 PM
From: Thierry
To: <zone6400@mac.com>

Hi,
a few months ago I wrote you about some info on how to overclock the bus
system. Now I have done the job and it's working ok, but not perfectly, at
45MHz and my Sonnet is up to 360 MHz. 
My set up is :
Performa 6400/200
136 MB EDO RAM
Sonnet 300/1 MB, 320 MHz with the Sonnet overcloker
Maxtor 40 GB 7200rpm
2nd hard drive (WD 10 GB 5400 rpm) in the SCSI bay extension with an
ACARD IDE to SCSI converter
3Dfx Voodoo 3 2000 graphic card
OrangeMicro PC 620
Scanner Mustek 6000CFX
CD burner Sanyo 8-2-20
"Frankenmac'ed" with a second power supply AT 200W (plugged in place of
the monitor - it powers both drives, the SCSI CD ROM player, and 2 fans.
Power cables enter by the TV tuner slot).

First I considered that I should have a possibility to move back to the
40 MHz crystal in case overclocking wouldn't work. A crystal connector
would do the job, and I found one on the Output Enablers
site, for free, with various 2 pin crystals - 40, 45, 48 and 50 MHz. 
After desoldering  the crystal and resoldering the connector (which
required to know more details I learned from Ed Nye), I tried the
crystals. I would get a start with the 45 MHz, but then freezes during
use - such as video playing. The 48 MHz would just allow a start up but
a rapid freeze. The 50 Mhz freezed the computer at start up. This is
mostly due to the stock 603ev processor, that overheats at these higher
crystal rates. I would have the same results with the Sonnet card, even
with the "scri" trick for loading the Sonnet extension first. So I went
back to the 40 MHz setting, and all felt with the usual snappiness. I
then purchased a Titan Copper VGA Cooler ( a fan more adapted to Voodoo
4-5000 graphic cards) and have installed it with silver thermic paste on
the stock processor. I then tried my different 45, 48 and 50 MHz
crystals with no L2 or PCI card on the MB, and as a test I read a
Quicktime video movie with the Quicktime Player (v 5) several times.
With the 45 MHz, it ran ok, with the 48 MHz I got freezes after a while,
and I could not even boot with the 50 MHz crystal.
So now I have installed everything back, my Sonnet 300/1 MB, Voodoo 3
and PC 620 card, and since two weeks I can work with this set up all
day, with my Sonnet doubly overclocked (bus + extension) at 360 MHz. 
Gauge Pro gives 35 MB/s, against 31 MB/s at 40 MHz.
Macbench 5.0 gives :
CPU 1180 - fpu : 1191 - Disk : 1485 - Publishing Disk 1147.
I am a bit disappointed about my 7200 rpm Maxtor result, because I could
get the disk score at 1300 with the 5400 rpm WD drive and was expecting
more improvement. Do you have a 7200 rpm drive and a Macbench score ?
The temperature is not different than usual, around 51¡C with some short
time peaks at 55 and 60¡C, but after passing to 51¡C (or about) the only
drawback I found is that I can't reboot the computer straightforward,
and have to shut it down for 4-5 minutes. This comes from the fact that the
stock processor is not idle when you run an L2 accelerator card, and it
can overheat, that is multiplier-dependent, inducing a freeze, that bus
overclocking emphasizes. It can be overcome either with a cooling system
or by lowering the
multiplier setting (see Ed Nye's site about this solution)
I did not try to set up the MB with a 48 MHz yet, but I want to try it, and
to overcome the expected processor overheat I want to go for a Peltier,
after cooling down my video card chip (I've found that when I add it, the
G3 processor's temperature rises). Peltier devices have the important
drawback that they generate condensation, and some reports were even
telling that after a few months the board got oxidized. I think of some
humidity absorber to remedy this. 
Of course, this is not as clean as changing the multiplier setting, but
that would be the next step if things don't go smooth. As I am not ready
to go for a newer machine (I use it mainly for text editing and the web
and I don't see the interest of going for a 2-4 x faster one), I will
follow these steps and see how I could push my Sonnet card ahead. The
only thing that I miss is the possibility of playing videos with no
stuttering, but there still are many things I haven't tried yet to make
it work.
All this was made possible thanks to the 6400Zone, so, Tom, long life to
your site!
Thierry