Re: CFINT

From: William A.(Tony) Corbett <corbett@asresources.com>
To: MIDRANGE-L@midrange. com <MIDRANGE-L@midrange.com>
Sent: Tuesday, March 05, 2002 1:00 PM
Subject: CFINT


> Hi guys,
> It seems to me that this whole CFINT thing has gotten out of control.  I'd
> think that IBM is using the same processor on multiple machines for
> production economy, and using the CFINT governor to make it different (MHZ
> in pc-speak).
>
> The overclockers of the world know that the same type of thing goes on in
> the PC world, solder a jumper, break a connection, or whatever and whamo!,
> your cheap processor has 50% more mhz than before.
>

You are confusing two things:
1) the interactive tax, Domino-only machines, and other purely software
governors
2) the differences between different models

The former is pure software (and can be overcome with software),
the latter is done with factory-installed jumpers (and can be overcome
with physical manipulation).

I'll not give away the game for the AS/400, but here is some info
from the internet on how to overclock an Apple:

Apples G3 PowerMacs are easily tuned, that means you can boost processor and
bus speed for no money. This is possible because Apples Macs have parts
running below their clock limit. BUT: Doing this you'll have to break (void)
the warranty tape on the motherboard.

So you're still willing to boost your Mac? Maybe this will help you: Some
month ago we overclocked a PowerMac G3/266 to 300 MHz and the machine still
runs fine. We've also tried to set the speed to 375 MHz and 75 MHz bus (by
mistake), then nothing happend. Setting it back to lower speeds the Mac
started again with no problem. Normally you won't harm your Mac, if the
speeds are to high it just refuses to start. But we won't give you any
warranty on success or tuning with no damage! We only give you some advices
here!

Let's go:
-1- Remove your Macs case (or open the MiniTower)
-2- Remove the warranty label. It's located in front of the three PCI slots:
-3-Under the warranty tape you'll find a jumper bridge containing several
jumpers. Here you can set processor and bus speed separately. The bus clock
also influences the PCI speed. Get some jumpers (just in case you loose one):
Jumper 1-4: processor speed (processor : system bus ratio)
Jumper 5-6: PCI bus speed (system bus : PCI bus ratio)
Jumper 7-9: bus speed
-4- Now go for it. See the tables below for the different jumper settings.
Note that the CPU speed depends on bus clock and the multiplier:
Jumper Nr.                                      Bus Speed       PCI-Bus Speed
Multiplikator
Bus : PCI
5       6       7       8       9
*       *       *                       66.7    33.3            2.0
*       *               *       *       70.0    35.0            2.0
        *       *       *               75.0    30.0            2.5
        *                               83.3    33.3            2.5

-5- Note: With the jumpers 5 and 6 you set the ratio between system bus and
PCI bus. Most PCI cards are built for a speed of 33 MHz, higher speeds may
result in improper functionality.

Jumper Nr.                      Multiplikator
CPU : Bus                     . CPU speed at...
1       2       3       4              66MHz    70MHz   75MHz   83MHz <== Bus
speed
        *       *       *       3.0     200     210     225     250
                        *       3.5     233     245     263     292
        *               *       4.0     266     280     300     333
*                               4.5     300     315     337     375
        *                       5.0     333     350     375     416
        *       *               5.5     366     385     413     458
                *               6.0     400     420     450     500
*               *               6.5     433     455     487     541
*       *               *       7.0     466     490     525     583

-6- How do I test the new settings? Simply turn on your machine. If it
doesn't move after the startup tune then the processor and/or system bus
(motherboard) are really overclocked. Simply switch back to a lower setting.
If the Mac starts up properly this doesn't mean that it also works properly.
If you get more programs terminated because of error type xy... then switch
back to the next lower processor or bus speed. We also experienced that the
machine worked fine but most applications started from the external harddisk
did terminate themselves after a few seconds. Besides, for testing purposes
you don't need to close your Macs case (or MiniTower).

A note on cache speed: Overclocking the CPU also increases backside cache
speed. The cache chips also have a maximum speed (varies from chip to chip),
so the cache could be a speed limitation before CPU and motherboard are
pushed to their limits. It's a good idea to set the CPU : cache ratio to a
lower level (default is 2:1, try 3:1 - G3 upgrade manufacturers do all have a
downloadable utility). This may help avoiding occasional freezes, but it
won't help you running a higher clock speed if the Mac freezes already before
loading inits.

====

Now try THAT on your AS/400 :-)