Topic: [ANN] Spondoolies-Tech - carrier grade, data center ready mining rigs - page 186. (Read 1260290 times)

70-100c only 1 was 100c

You are not missing anything. mdude77 is correct in that it depends on your local electricity price. But it also depends on whether you are planning to buy units or already have them.

If you already have the units, then your goal might be to maximize net income. See https://bitcointalksearch.org/topic/m.10146041 for an example. The higher your electricity rate, the more it makes sense to underclock existing units. Your net hashrate will decrease due to the underclock, but your electricity usage will decrease even more with the result that your net profit (income minus expense) actually increases.

In your example you have used a fixed power budget (4200W) and have taken into account the purchase of either 6 underclocked versus 4 stock units. That is a different calculation and, in this case, you are correct in that buying 6 units only to underclock them may not make sense in terms of return on investment. i.e. buying 4 units and running them at stock speeds may recover your initial investment cost sooner than buying 6. But even here it depends on your electricity costs; if your costs are high enough it is possible that stock units will run at a loss (i.e. you will never recover the purchase price), while underclocked units will run at a profit ... meaning that buying 6 underclocked units make more sense than buying 4 stock units.

Or, as the artificial intelligence WOPR concludes in the the 1983 movie WarGames, sometimes "the only winning move is not to play."

That's why I used a fixed wattage so that the electric would be the same in the comparison. It's just additional hashrate at lower w/gh but higher $/gh.

Depends on your electricity price.  At current BTC/USD value, I'm losing money running at stock.

M

Take a look at your chip temps.  They are more important than the temp of the air leaving the machine.

So besides noise & heat, does it really pay to underclock vs. stock on the SP20?  I tried to run the numbers allowing a total of 4200 watts at the units (not wall).  I used 700w for underclock at 1200gh/s and 1200w for 1600gh/s.  My calc shows about $697 higher price for 6 underclocked units vs. 4 stock units.  The underclocked higher hashrate would take over 600 days to return the higher price of underclocking.

Am I missing something?

What temperature should I aim for to prevent harming the SP20?
I am reaching 78C on Back T,B with 23C intake.
Also does anyone have a calculator or chart showing effeciency ?
Clocking it down to around 1050GH gets me around 0.51 watt per GH.

You did not!!
my error!!! 
I only saw new name DC-W which I confused with w=wall (which by the way makes no sense as it is AC at the wall).
you new entry "wall watts" matches my PSU and measuring very well!!  (y)!

Prices are great these days but I must say it's a bit sour that I could have basically not bought an SP30 at all back in august and bought it instead today, and I would have saved money overall. In other words the miner prices have fallen faster than the revenue.

Two underclocked SP20 report 681+682 watts=1363 watts at the wall, but kill-a watt reports 1424-1425w for the same two (nothing else is connected to kill-a-watt).
SP20, i assume, should be able to measure precisely. Can kill-a-watt be so much off or Sp20 showing 'theoretical" at the wall assuming gold/platinum PSU, hence a difference because I use CX750M bronze?
EDIT: OP posted that it is basically "theoretical" at the wall, assuming 90% efficiency. Increase by at least 5% if you use Corsair CX750/CX750M bronze. In my case 2.6.7 shows ~680w "at wall" while it is actually ~712.5W.

put out the 4 screws from the controller board to unconnect the fan.

Would you be able to put the fan speed in the API output please, ideally in both cgminer and /monitor.php?

Thanks.

M

Not everything goes smoothly with auto. On one machine, loop 3 gets temporarily disabled (upper image). cause? once i switched from auto to fan 10, everything is back to normal (lower image). on the second machine this did not happen, so maybe it is sporadic.

Thanks to the auto fan i was able to bump it up 0.64/0.65 settings and stay under the 20% fan it used to be. The heat is a bit more, but at least the noise in my office is WAY down with 3 of them with a bump in speed  

I have a situation where at fan 20 almost all are at 85C, but one is stubbornly at 100. since it goes by a single chip with the highest temp, i wonder what my fan setting would be. If close to where it started, then it is not even worth doing. Instead, i can just pick 10, then modify voltage until the "worst" chip is at 115. In any case, it is a very cool feature.

If you want to replace fans-I finally opened one SP20 and I don't see how I can disconnect the stock fan from the board connector unless using some bend tweezers. the connector is upside down and not easily accessible.
Are the sides even removable?  The sides they have these round hole screws-are those removable as well?

all 8 are now on auto waiting for them to settle a 6% fan

is this thread also the right place to put in some feedback or bugs?!

I experience some failes to display the working pools from cgminer in the main Page. This appears randomly after some hours, but cgminer is working fine with connections to these pools?! May belong to the API-Allow problems I had with allowing Subnets and that strange backslash?

Next bug is that one sp20 is probably rebooting at least twice after a power of so that it needs at least 5 Minutes to be ready to mine.
will try to save the logs next time.
edit:
http://ge.tt/8ESNew82/v/0?c

any ideas?

 these 2  screen shots should help.  I am doing 1 miner that is running around 1100gh.




I was on 20 I am picking auto




 6%  1132 gh

Awesome, thanks!