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Macintosh powerbook Pismo processor
card PowerLogix G3/900
|
Philippe Helman
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WARNING : everything below must not be done if you
hesitate, just a little!!!
Nobody will be responsible if you try it and damage
something!!!
Featuring :
Powerbook G3/400 « Firewire » processor card
upgraded to G3/900 (750fx) by PowerLogix.
512 Mb RAM (2x256 PC100 CL2).
Running 10.3.2.
Note : The original card had L2 cache problem. Except
that, it worked.
As the G3/900 does not use original the 1Mb cache but its
own 512Kb on-chip, an upgrade is allowed.
It made indeed no problem.
The original double heatsink is not used anymore by
PowerLogix because the G3/900 installed processor final
height is 1,7 mm above original one.
Therefore, PowerLogix provides a 1,3 mm thick single copper
plate of 35x65mm size to be glued with thermal paste both on
the processor AND under the metal plate covering the
processor card.
As I was not fully convinced of the efficiency, I reworked
the original heatsink to use it again.
750fx processors have no built-in temperature circuit so no
software (TherminDock, Thermometer, Thermograph) can display
temperature anymore.
To check the improvements, I made some temperature
measurement with a K-type «film» thermocouple
inserted between the metal plate and the heatsink.
I did NOT inserted the thermocouple between the processor
and the heatsink, because the thermocouple is made of metal
and risks of touching the electronics are too big.
I made a comparison between PowerLogix and modified Apple
heatsinks, and I also measured with an original 500MHz
processor card.
The read values are for comparison only and do not represent
the real processor temperature.
The following pictures and legends show the steps of the
tests.
1)
Before any test, I measured the height difference.
Here is an original G3/500.
2)
The G3/900 is obviously higher... by 1,7mm.
3)
As received, with the plastic shield to avoid metal
contact with the heatsink.
4)
Plastic shield removed...
5)
Shows intermediate printed circuit board. It is amazingly
well done !!!
6)
The copper heatsink and the thermal paste provided.
7)
To glue the copper plate on the metal plate.
8)
And the small drop on the processor.
Later, I put Artic silver 3 thermal paste, but no specific
improvements were noticed.
9)
Was tested under 10.2.8 and 256 RAM at the beginning.
10)
Carefully remove the original patch form Apple heatsink
11)
And remove the glue.
12)
After unbending the heat-conductive pipe by around 45
degrees, I carefully removed the processor-side plate.
13)
It uses soft-soldering, so quite easy to
«unweld».
14)
Fine-tuning the path of the pipe, going above the card
but beside the processor, and with the top of the pipe
leveling the top of the processor
15)
The 1mm thick brass plate was carefully positioned and
welded on the other side of the pipe, using a special fluid
to allow a best contact between pipe and plate
16)
It is originally designed for copper welding in central
heating piping works, using Ag-Sn (silver-tin) alloy. It
contains an acid, so be careful!!!
I used another Sn-based alloy (Sn-Pb) because its melting
temperature is far below Ag-Sn.
17)
After cleaning the plate
18)
Thanks to the soldering fluid, the alloy perfectly fills
the space between pipe and plate.
19)
Installed with part of the thermal patch.
Fitting and tightening the metal plate will press the plate
on the processor.
20)
This is the K-type (Chromel-Alumel) industrial
thermocouple.
It has a specific film-designed sensor and is as fragile as
expensive !!!
21)
The Keyboard was not fully reinstalled for tests.
I did not want to remove the airport card, even if it was
then possible to let the wire go through the PCMCIA
slot.
22)
It shows 62 degrees Celsius.
This is a stabilized temperature after a 1 hour work (word
processing).
The temperature at the second cooler (the metal visible one
on picture before) is around 50 degrees Celsius.
23)
Running several (10x) Xbench raised temperature to 67-68
deg C.
24)
25)
At that temperature, I got a freeze twice!!!
The cooling fan never started.
26)
It shows what it shows...
27)
The temperature sensor installed on the PowerLogix copper
plate.
28)
Now with the PowerLogix copper plate.
Temperature raises faster than with my heatsink.
29)
Word processing keeps temperature at 66-67 deg C.
30)
Only one Xbench froze the Pismo.
After restart, a Dropstuff test raised the temperature up to
70 degrees C, then froze again.
Note that with the 500MHz, TherminDock showed once up to 72
degrees C, and the Pismo started to slow down... without
having the fan started.
31)
Well, sensor position was not installed between heat
exchanger and thermal pad, but above thermal pad, because I
did not want to remove this pad. Note that this heat
exchanger is made of a kind of black plastic, still with the
heat pipe (in copper). This is part of a revision 2 Pismo
model from september 2000 (including motherboard revision
for Firewire improvements, and a 20GB hard disk instead of
the 12Gb on the 500MHz model, from 6 to 10 Gb on 400
ones).
TherminDock was running with the original 500.
And obviously, it was hard to raise processor temperature.
32)
After 15-20x Xbench (CPU and Quartz only, to run
processor at 100% load as displayed by Menumeters),
TherminDock showed maximum 72 deg C while the K-type sensor
showed a heat exchanger temperature of 58 deg C. TherminDock
shows a very fast temperature drop when Xbench test stops
(from 64 to 52 in 5-10 seconds).
TherminDock showed very briefly 76 deg C but Xbench then
quit. I was not able to reproduce it.
And the fan did not go off. I never found the Apple official
start/stop temperatures for the fan. Neither on the Web, nor
in the service source, nor in the developer pdf. If you have
a serious source Maybe ambient air temperature is in cause,
at 20 deg C it is fresh for the Pismo.
I guess during summer season, with an air at 30 deg C in the
room, the original 500 will freeze. The underside of the
Pismo was less hot than with the 900.
You will find in this file the comparative results of
various tests in various configurations.
This will not apply to you, you should only compare the
time gap for the same task, for example.
Original machine :
Pismo 2x256RAM 2-2-2, thousands of colors, OS 10.3.2, on
AC adapter, combo drive (24x CD read) inserted, no
battery
Network : all active : Modem ready, IrdA OFF, Ethernet on
fixed IP but not connected to hub, Airport card present but
OFF
HD : 20Gb/2Mb cache/4200rpm (new), or 40Gb/8Mb cache/5400rpm
(new), same files on both
Comparative machine :
G4/533 3x256RAM 3-2-2, millions of colors, OS 10.3.2, 2
optical drives (40x CD read), ATI8500
Network : all active : Modem ready, Ethernet on fixed IP and
connected to hub
HD : 1x40Gb 7200rpm + 1x60Gb 7200rpm
Results in seconds
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256 RAM
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512 RAM
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TOWER
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REMARKS
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Test
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500/20
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500/40
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900/40
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900/40
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G4/533
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Boot
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80
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57
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60
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60
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64
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from pushing button to ready to work
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System profiler (speed/cache)
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500/1
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500/1
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900/512
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900/512
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533/1
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Copy 1 file
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duplicate 1 file
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5
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4
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4
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37Mb .dmg (10.3.2 update)
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duplicate 1 file
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22
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19
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28
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27
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16
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189Mb .toast
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CDtoHD
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120
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124
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100
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280 Mb .mov (Panther_demo)
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extFWHDtoHD/return
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22/46
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22/45
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12/13
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"
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Copy x files
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duplicate x files
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5
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4
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4
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4
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53 files, 36Mb (.pps, .jpg, .mpg, .wmv,
)
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duplicate y files
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187
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177
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158
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155
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145
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>2800 files, 580Mb (user library folder)
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CDtoHD
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166
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148
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123
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78 files, 23Mb (choix redaction folder)
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extFWHDtoHD/return
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11/13
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11/13
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8/9
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"
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Stuff 1 file
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std 802, dmg to sitx
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164
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165
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113
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120
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37Mb .dmg, no compression result
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Stuff x files
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std 802, folder to sitx
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183
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182
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125
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128
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139
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566 files, 68Mb > 29Mb
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Unstuff 1 file
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std 802, sitx to dmg
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106
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105
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|
70
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88
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37Mb .dmg
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Unstuff x files
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std 802, sitx to folder
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127
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124
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87
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85
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104
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566 files, 29Mb > 68Mb
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Unstuff x files
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std 703, sitx to folder
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124
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127
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-
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-
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102
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566 files, 29Mb > 68Mb
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Launch soft only
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Netscape 7.1
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13/10
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14/10
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12/6
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11/6
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14/7
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1st/2nd lauch
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Excel X.1.5
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6/3
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6/3
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-
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4/2
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5/3
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1st/2nd lauch
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Photoshop 701
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21/13
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21/13
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16/10
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15/10
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15/11
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1st/2nd lauch
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PS701
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67Mb file open
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32/26
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23/19
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-
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20/17
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22/18
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1st/2nd lauch
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67Mb filter
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32
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32
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-
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23
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15
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gaussian blur 25 pixels
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iTunes 4.2 encode
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AIFF to MP3, 192k
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3.3x
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4.2x
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5.8x
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8.0x
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8.0x
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42Mb AIFF file on HD (4'12")
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Tests and compatibility
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Xbench 113
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CPU speed/cache size
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500/1
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500/1
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900/512
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900/512
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534/1
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cache speed
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200
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200
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360
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360
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267
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CPU
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34,2
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34,2
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61,3
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61,1
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63,7
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disk
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53,5
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57,7
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59,7
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58,8
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90,6
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graphic Quartz
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61,1
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61,2
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89,4
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89,7
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102,5
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graphic Open GL
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67,9
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68,2
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111,5
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113,3
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65,2
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CPU Director 1.3
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CPU speed/cache size
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900/512
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900/512
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533/1
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cache speed
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900
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900
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267
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iChatAV support
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DV FW camcorder
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-
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No (1)
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-
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No (1)
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Yes
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(1) Yes with APE 1.4.1 and iChatUSBCam 1.1.2
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iSight
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-
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No (1)
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-
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Yes
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Yes
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IMPORTANT UPDATE April 2004
I installed the 900 MHz in another Pismo, running
10.3.3.
And, after 1 hour working hard in a hot car (with Airport
connected to a hotspot), I heard the fan coming ON.
It ran for 20-30 minutes.
This was reproduced several days.
I can't say it is the change of Pismo, or 10.3.3 (all tests
were made under 10.3.2).
I might suspect 10.3.3 because I read Apple changed the fan
start temperature level in the software, after people
complaining about heat feeling on PowerBook Aluminium G4 12"
mainly
Conclusion :
I would not trust the PowerLogix heat exchanger under
heavy processor load!!!
Even word processing raised the temperature, no matter how I
carefully cleaned and put new thermal paste at each
installation.
My modified heat exchanger stabilized the temperature but it
is still not reliable under continuous load.
Nevertheless, I have NEVER met a freeze with the mod when I
normally work (processor under various and varying loads) :
playing with Xbench or Dropstuff is not a matter of
hours
Furthermore, using Artic Silver 3 thermal paste slowed a
little the temperature raising speed under heavy load : heat
transfer is faster to the heat exchanger.
I made some test by downclocking the processor to 500 MHz
thanks to CPUDirector v1.3.
Continuing text editing showed the temperature dropping to
57-58 degrees C.
Xbench was not able to dangerously raise the
temperature.
But what, I have a 900MHz, I want to fully use it !!!
...
SO
...
WHAT???
Well, too hot is too hot, and temperature margin is too
small for me.
I asked one of my colleagues, whose hobby is electronics, to
help me.
The cooling system specs sheet included :
- use original fan (5 Volts, 0,5 Watt) but not
motherboard circuit
- control circuit must be OFF when Pismo is OFF
- control circuit must be 5 Volts powered and as low
consumption as possible
- triggering must include an hysteresis (fan starts at
X deg C and stops at Y=X-Z deg)
- Start (X) and stop (Y) temperature must be
adjustable, at least on prototype
- Temperature sensor must be as closed as possible to
the processor
- The accuracy of the sensor should be +/- 1 degree
C
- Printboard must be maximum 5 mm thick, components
included, anb will be located above the hard disk
- 5 Volts may be taken from hard disk power supply
- circuit must be protected by a fuse (or a similar
electronic system with automatic reset)
We rapidly forgot about Peltier effect cooler, their
power consumption being far too high.
Surprisingly (for non-electronic fan), he needed 5 minutes
to design the circuit !!!!
Parts cost was estimated below 50 Euros.
Of course, handmade printboard is time-consuming, and if you
have to pay for it, forget it!!!!
On the other hand, if you are careful and have the
appropriate tools, go for it!!!
As time is missing, the above temperature control will be
part of a future release.
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