At 10:23 PM -0400 7/28/99, Mike Jarjoura wrote:
>With the limited background I have in Electronics Engineering, I would like
>to offer what I know. There are many factors to an upgrade like this, to
>name a few factors...
>
>1) is the pin configuration the same on the 300Mhz 603e and the 100Mhz 603e.
There are two things which seem to be potential issues here, one far more
serious than the other.
The first is that the 300 may provide for more bus multiplier settings. (I
haven't looked at the relevant tech docs so I don't know, but it seems like
a logical possibility.) This is not too great a worry, though -- lifting a
couple pins and connecting them to dead-bugged pullup or pulldown resistors
is the least of your worries. :)
The second is that the 100 to 133 MHz 603e speed grades use a 3.3V supply
for I/O pins and 3.3V for core logic supply. The 166 MHz and up versions
use 3.3V I/O and 2.5V core logic. This is a BIG issue, and one I didn't
think of before you mentioned this.
Unless the designers of the Duo motherboard provided a special plane for
the core logic supply and provided a split point where it can be cut away
from the 3.3V supply (thus allowing you to substitute power from a 2.5 volt
regulation circuit), I'd say this is probably insurmountable.
It's possible that the chip may operate despite the increased core voltage.
However, you then run into a big power problem. The power used by a CMOS
device is proportional to the square of the voltage, so an estimate of the
increase in power is to multiply the quoted power use by 3.3^2 / 2.5^2 =
1.74. The 300 MHz 603e normally uses 4 W average. 4 * 1.74 = ~7 W. Not
good.
>2) will the bus speed of the Motherboard allow a 300Mhz upgrade. FCC rules
>may prevent this upgrade and high freqency radio waves off of the busses and
>Motherboard, etc. might cause the book to function oddly.
To make 300, you probably do need to overclock the bus.
The FCC may not like it, but I don't think they have any jurisdiction over
this sort of thing (you're not going to turn it into anything even
approaching a real radio transmitter, after all). And it's not likely
they're ever going to test one.
>3) the un-educated fearful comments made about unsoldering the IC's are not
>correct. Unsoldering chip's is done with heat sink/heat dissipation tools,
>and a low-watt DC "IC" soldering iron. No sweat to a tech...Keep in mind
>though that you can seriously fry these Microprocessor Chips with a zap of
>static alone, so profess. care should be taken.
Heat isn't the big problem. Damaging the pins is. The pins on a
fine-pitch QFP package are very fragile and typically do not survive the
removal process (of course, usually techs aren't trying to preserve them,
since this is usually done to replace a defective part).
QFPs are generally difficult on the assembly side too; they're shipped in
special trays which prevent the pins from touching anything, and you're not
supposed to directly handle them at all (you use a suction wand to pick
them up by the top surface). Once the pins are soldered to a board,
they're OK, but until then they're far too easy to bend. Once bent, it can
be very difficult to get them back into good soldering position, especially
because it doesn't take many bends to fatigue the metal and break the pin
off.
>4) is the running temp. of the 300Mhz hotter and if so, how hot?
Not much, if at all. I looked up the power use of the respective
processors when this first game up and it's pretty similar (both are around
4 watts average, 5-6 watts peak). Of course, as above, this changes if you
can't get the right voltage power supply.
> Is there
>room to fit an after market ribbon heatsink? A "IC" cooling fan?
Doubt it, usually in notebooks there's no room for anything extra at all.
>5) Apple tech's should have all of the necessary tech data on the 300Mhz
>603e. Investigation could start there.
Motorola's web site has everything relevant.
http://www.mot.com/SPS/PowerPC
>6) is the physical size of the 300Mhz 603e different?
The die may be a different size but the packaging should be the same.
Provided that you're talking about like packages, of course.
>7) is the power requirements of the 300Mhz 603e within the ability of the
>Powerbook?
>
>8) battery life may be affected by this upgrade.
See above -- disregarding the core voltage issue, the power use should be
about the same.
Tim Seufert
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