on 1/10/01 Bob Friede rlf9 <[EMAIL PROTECTED]> wrote:
> Sidney Ho wrote...
>
>> I've had a Newer G3/240/512kb die from (partially) heat related causes (in
>> August, when temps could run 168-170F on the G3 CPU). Fortunately, Newer
>> replaced this under warranty before they went bust. Ambient temperature, air
>> circulation and the type of surface the 2400 is placed on are important
>> determinants in heat transfer efficiency. I've added an aluminum block to
>> connect the CPU directly to the aluminum pad of the lower case housing the
>> convection tube.
>
> Any chance of a step by step how-to?
Groan...Well, as lazy as I'd like to be, it's hard to refuse such a direct
request and actually a quite IMPORTANT modification.
Heat reduction of the CPU is extremely important. The cooler it is the more
stable it will run and the longer it will live. It will even run
(un)measurably faster as heat increases conductivity resistance. The
original 603e/180 mhz runs quite hot. The Newer G3/240mhz runs hotter. In
winter, room temperature on a hard desk surface, I'm running 62 C / 143 F
under constant normal load. A summer temperature might be 10-15 F higher,
but I haven't monitored it so closely since I had to reinsert a G3/240 to
replace my failed G3/320. I turned the backside cache back down to the
standard 120 mhz from the accelerated 160 mhz. The latter does cause
increased instability and heat while little speed increase is to be noted in
the real world--or even with MacBench. With no more 2400/G3 upgrades likely
to be available, survival/reliability over speed becomes a paramount
consideration. For reference, my own MacBench 4.0 (without LibMoto) tests
scored:
G3/240 at 120mhz 160mhz backside
Processor 756 783
Floating Point 597 598
Disk 308 310
The modification is actually quite easy, assuming you know how to reassemble
a 2400c.
1. Disassemble and pull out complete motherboard (MB) and I/O power board.
You will see an aluminum heat sink block about 20 x 20 mm x 2-3 mm thick,
sitting on top of a hollow cavity, with a convection pipe leading towards
the PC card cage.
2. Take some aluminum foil sheet, fold it repeatedly until it is about the
same size (L x W) of the heat sink and about 1.5-2 mm thick (this is about
the air space between the CPU and the heat sink). Compress this foil block
to eliminate any residual air pockets and maximize its density, even
crimping the edges with pliers (if necessary).
3. Glue (lightly) the foil block on top of the heat sink. The objective is
to maximize the heat transfer efficiency from the CPU ASAP through the heat
sink so the natural air convection can optimally dissipate heat buildup.
Replace the MB and reassemble the 2400c. The CPU will then sit flush over
the foil. I think this modification lowers CPU temperature by around 15 F, a
big difference.
Sidney Ho
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