On Dec 30, 7:26 am, David Kelly <da... RemoveThis @futuresbright.com> wrote:
> I'm a bit suspicious about this whole "you need to replace the CPUs"
> diagnosis. The machine was running fine when I took it in, it's just
> that the water pump made a horrid noise and the machine ran a bit hot.
> Surely this is a cooling system issue!?
Yes, that sounds like a cooling system issue...the questions are, "Was
the water pump's horrid noise caused by it overstraining itself to
keep up with the attempt to cool, and if so, was this caused by a
deficiency of the A) the pump, B) the ducting, C) the heat-sinks, D)
the coolant, or E) the circulatory system as a whole; and if the noise
was not caused by over-strain, what was its cause? Finally, 'the
machine ran a bit hot' and did this damage, say, the sensitive caches
of the central processing units?" The answer to each of the first set
of questions is answerable by disassembling the cooling-system and
pressure-flow testing each stage in isolation (first bad, last good--
same as power-flow in an electrical circuit; note that this is done
with fluid and Not In A Computer!) if you have a friend who works in
HVAC (High Voltage Air Conditioning) or a good collegiate chemistry/
physics lab or industry, he may be able to check this for you or tell
you who can; the second question would only be answerable, really,
once the cooling system has been tested and any necessary replacements
made, or by swapping the CPUs themselves in isolation to another
machine for testing, as it would require the use of thorough
diagnostic software to test every processor function in each CPU.
Personally, I'd check the forums and articles on liquid-cooled
overclocking on websites such as Tom's Hardware and PC Modder , as
well as the customer forums of Dell (which makes a water-cooled XPS
gaming computer) and of
http://www.newegg.com (which sells water-
cooling kits and equipment). Between these sites and their forums, I
bet you can troubleshoot your issue, determine probable causes, and
source any parts you need to get your rig running right (so long as
it's not the CPUs themselves that are running hot--and even then,
better cooling...). As long as your heat-sinks' ducting is not
corroded-through, you should be able to flush them and keep using them
(just as you'd keep your car's radiator, not pitch it out and replace
when you need new fluid). As long as your heat pipes can be flushed
adequately and are unholy, you should be able to keep them. That
leaves the pump (maybe US $30-75.00) and coolant. Then again, you may
decide to ditch the whole cooling system and replace with new; (last
time I looked, a bit less than two years ago) made-by-you generally
costs in the vicinity of US $125-250.00 if you have to buy rather than
scrounge / adapt, while made-to-order generally costs roughly double.
The higher-end cost-range includes things like cooling not only the
processor(s) and motherboard but also the video card(s) and hard-disk
drives. If your CPUs aren't shot, I'd say even a high-end made-to-
order liquid cooling system would be a good deal cheaper than the new
processor set. Perhaps they were looking at buying from Apple, and
couldn't buy replacement heat-sinks separately? I haven't seen anyone
use non-Apple heat-sinks on a G5, but I've seen many accounts of G3/G4
ZIF systems running Pentium III / Socket 370 processor heat-sinks with
the groove for the heat-sink spring-latch re-milled, as the larger and
better after-market P3 heat-sinks allowed significant overclocking.
Ingenuity and inspiration will frequently keep pace with a larger
budget! OTOH, look at this as an opportunity to source Dual-Core Dual-
G5-Processors? If I were spending seven-hundred pounds (what's that,
about US $1,400.00 right?), I'd be looking at all options!
>> Stay informed about: What to do with broken PowerMac? 
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