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Old 2014-09-13, 07:43   #23
Mark Rose
 
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I'm no chemist, but nickel oxide is green while copper sulphate is blue, so I imagine it's nickel oxide that you're seeing and not copper sulphate.
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Old 2014-09-13, 18:48   #24
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There is an experiment I would still like to do some day. You take some pennies and dip them into a boiling mix of powdered zinc and sodium hydroxide to plate the penny in zinc to make them look silver (although the cooler part is fusing the zinc and copper to make brass (gold) pennies).

The mix needs to be just below boiling to work, which makes me think that the copper fins might have been warm enough to trigger the reaction. Cupronickel is silver in colour.
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Old 2014-09-13, 23:45   #25
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Quote:
Originally Posted by TheMawn View Post
There is an experiment I would still like to do some day. You take some pennies and dip them into a boiling mix of powdered zinc and sodium hydroxide to plate the penny in zinc to make them look silver (although the cooler part is fusing the zinc and copper to make brass (gold) pennies).
Coincidentally, Canadian pennies from 1997 to 1999 were copper plated zinc...
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Old 2014-09-14, 04:12   #26
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Quote:
Originally Posted by Mark Rose View Post
Coincidentally, Canadian pennies from 1997 to 1999 were copper plated zinc...
Yes.. I read somewhere the experiment doesn't really work with those particular ones. But that might have been someone substituting drain-o for the sodium hydroxide and galvanized nails for the zinc.
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Old 2015-03-02, 13:55   #27
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in reply to a post in a different thread:
(trying to keep my stuff together in this thread)

Quote:
Originally Posted by Mark Rose View Post
What do you have in the way of radiators on that loop? I am curious.
Two of these, with 12 of these (each one of the first can accommodate six of the second, three on each side, but never running all 12, usually 4 or 6, change them from time to time; if the air is hot even running hundreds won't help, and if it is cold, 4 or 6 are enough), two of these (no PWM, they max always), one outside the house in the rack, one inside the room on the floor behind of the computer, it helps with the flow, and a custom combination of these (about 5 liters total volume). When under 30ºC outside, it can sustain 4x 580s plus the CPU. If the water runs fast, it gets out from the computer only half degree to 1-2 degrees hotter than it gets in.

edit: the orphan pump and the holes on the wall where the hoses go out; the small one is a 25 wires cable with all the command (fan pwms, outroom pump, etc)
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Old 2015-03-02, 14:13   #28
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and the rack outside, sorry for the quality of the photo, is from the window, no way I could go out there now, you know snakes, scorpions, ghosts, etc...
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Old 2015-03-02, 16:50   #29
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Quote:
Originally Posted by LaurV View Post
you know snakes, scorpions, ghosts, etc...


Neat though! That gives me some idea of what is needed in the way of cooling for running flat out.

Have you ever had trouble with condensation on the intake pipe in the cooler months?
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Old 2015-03-02, 17:14   #30
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LaurV, interesting setup. Thanks.

I've been developing a low-cost, gpu-centric heterogeneous computing system combining several desktops. Some computations create large electricity/heat spikes which I've sought to address economically. Adding more fans and/or liquid cooling creates more of a burden than a solution. Has anyone used piezoelectric fans between gpu's in a multi-gpu rig?

Analogous to the D870 design, I've looked at external gpu boxes. Is anyone using these kinds of rigs? One of my goals is to develop a modular and piecewise upgradeable fault tolerant system ..if one PC blows up the others can still carry on.

Aspects of cloud computing may help with fault tolerance but statements like "There is the problem of legal ownership of the data.."
from Wikipedia do not give me a warm and fuzzy.

Last fiddled with by jwaltos on 2015-03-02 at 17:55
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Old 2015-03-02, 20:55   #31
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The above is the front end for running calculations which I'm experimenting with. The back end is an old Xeon running a C2050 with ECC to develop any patterns found in the front end symbolically and to re-run any questionable results for confirmation. Again, this is a hot system with the Tesla at 85 C despite the fact that the surrounding temperature is between -20 -> -5 C for the air intake.

Trying to balance the hardware and software to make this whole system fly reminds me of the alien in District 9 toiling away to obtain enough goop and in another sense, the movie Pi.

Last fiddled with by jwaltos on 2015-03-02 at 21:22 Reason: Corrections.
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Old 2015-03-03, 03:11   #32
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Quote:
Originally Posted by Mark Rose View Post
cooler months?
Ye dreaming, hehe, "cooler months" here mean +12C in the morning, since 15 years the lowest I ever saw in my area was a very cold end of November few years ago when it dropped to +9C, and usually the "winter" here corresponds to the "dry season" (no rain from about end of October to May, with very few exceptions, there are few rainy days in March, called the "mango rain", because if it rains at that time the mango fruit gets bigger and sweeter). I never seen "condensation" in this period, even the dew is extremely scarce and the grass under the threes dies (the other is still receiving some dew in the morning and survives) if ye don't water it. Sometime I really envy your guys living in colder countries, and I am missing the snow, and think nostalgically to Romanian winters, with -20C and one meter of snow... What a data center I would do there... (assuming I can lock the same income, of course, hehe). I would not have the cooling problems I have here... fighting the heat 10 months per year... But on the other side, no money spent on coats, boots, preserves, etc, I have fresh fruits all the year and I can go to job with the same shorts and t-shirt 200 days a year...

Edit, P.S. related to condensation, I wanted to try therocouples (for example peltiers, you can buy them very cheap from ebay now) but some of my friends scared me off with condensation stories/nightmares. I will try them in the future for sure, when the time/budget will allow.

Last fiddled with by LaurV on 2015-03-03 at 03:23
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Old 2015-03-03, 04:18   #33
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addition, edit time limit
Quote:
Originally Posted by LaurV View Post
Ye dreaming, hehe, "cooler months" here mean +12C in the morning,
and that only 10-20 days per year, the rest the minimum is +16C,
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