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Author Topic: Mining Hardware Mistery [127.5 C / 0 RPM]  (Read 2447 times)
DeathAndTaxes
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Gerald Davis


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February 10, 2012, 02:07:02 PM
 #21

One mystery still eludes me, what is the significance of this magic 127.5 C ?

I don't think there is any.  When electronic devices don't get enough power they can display all kind of garbage data.

Quote
last night I inspected the extender cables and they are in very poor shape, I re-soldered some of the connections that have come lose and it allowed me to get the rig back up, one of the pci extender cables is beyond total repair (its amazing to me the thing works at all considering there are at least 5 leads that are un connected where the ribbon cable meets the pcie slot) so on that extender cable I replaced the 5870 with a 5830 so there would be less power draw. This allowed me to get the rig back up until I get the new extender cables, its obvious to me that these things are hand soldered by Chinese graduate students, and they do not last forever.

Yeah if the PCIe extenders are in that bad of shape the resistance is going to go up and thus it is going to mean more current, possibly more than the MB can supply.
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cablepair
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February 10, 2012, 02:12:18 PM
 #22

why is it exactly 127.5 c every time?

also I have seen reports from others that have seen this 127.5 interesting enough the other one that reported it here had almost an identical setup

garbage data it may be but there has to be some significance to that exact number appearing it must mean something...
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Gerald Davis


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February 10, 2012, 02:18:55 PM
 #23

why is it exactly 127.5 c every time?

also I have seen reports from others that have seen this 127.5 interesting enough the other one that reported it here had almost an identical setup

garbage data it may be but there has to be some significance to that exact number appearing it must mean something...

Not really. The temp isn't stored as a floating point number "127.5" internally it is some binary numbering system.  127.5 could simply be all zeroes internally and when the device fails due to voltage sag it goes to 000000000 which the drivers interprets as 127.5C.  I am not saying that is the exact reason but if the card isn't getting enough power it isn't operating according to the assumptions made when designing it and thus garbage in -> garbage out.

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February 10, 2012, 02:25:44 PM
 #24

why is it exactly 127.5 c every time?

Just a guess, same reason old bioses are limited to 127.5 GB: 32 8 bit registers. Sensor stores data in a 32 8 bit register, gives 256 possible values,  which is mapped from 0C to 128C with 0.5C precision, and perhaps one reserved for error state or whatever. You would probably get the same value if you pulled a power cord from a running GPU, but Id recommend not testing that theory.

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Gerald Davis


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February 10, 2012, 02:26:56 PM
 #25

I am sure you meant to type 16bit. Smiley
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February 10, 2012, 02:38:07 PM
 #26

Im sure we both meant 8 bit Smiley

DeathAndTaxes
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Gerald Davis


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February 10, 2012, 02:39:26 PM
 #27

Im sure we both meant 8 bit Smiley

DOH, and with that I go to get some coffee before I hose some databases up.
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February 10, 2012, 05:52:18 PM
 #28

I am leaning toward the PCIE extender cables.  I restarted my troubled miner this morning and GPU 2 read 127.5 and 0 RPM for about 15 seconds then it showed the correct temp/rpm.  I also checked the fan and it was up to speed when it said 0 rpm.

I am going to order some powered PCIE extenders and see if that makes a difference.


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