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April 21, 2014, 03:05:36 am

Author Topic: Cgminer and GPU #  (Read 2128 times)

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Offline BitJohn

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Cgminer and GPU #
« on: May 12, 2013, 11:25:36 am »
How does cgminer determine which card is which in the gpu 0-4 scenario? IT seems to change occasionally or am I just seeing things?


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Offline spincycle

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Re: Cgminer and GPU #
« Reply #1 on: May 12, 2013, 12:13:45 pm »
For my cgminer running on linux, the GPU 0 always seems to be the card highest on the motherboard. The temperature can run 10 degrees higher and I believe that is due to the lack of airflow and having the GPU 0's fan sucking hot air off the GPU 1 card hence making the temperature higher.
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Offline JesstersDead

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Re: Cgminer and GPU #
« Reply #2 on: May 12, 2013, 12:22:14 pm »
PCIe mapping varies from mobo to mobo, though typically GPU 0  is in the primary x16 lane. However, it is static once mapped. Otherwise using a -d 0 or -G 1 would be pointless lol. Most if not all OC'ing software like Trixxx and Afterburner use the static map as well, so you could see how problematic a variable PCIe map would be if you have software that applies overclock settings at startup.


@Spin

Yep, hot air rises lol. If you have enough space between the cards I would look at getting a PCI slot blower fan to help vent the area between the cards. I have this same problem on my gaming rig when mining, and installing one of those did help slightly.

Offline spincycle

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Re: Cgminer and GPU #
« Reply #3 on: May 12, 2013, 12:25:45 pm »
Hi Jester,

That is a good idea. There is one regular pci port between the two cards with plenty for some sort of pci fan add-on.

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Offline BitJohn

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Re: Cgminer and GPU #
« Reply #4 on: May 12, 2013, 12:26:15 pm »
Ok so whats wierd to me is my 7950 has high RPMS for a fan at 70% since its a blower. Looking at cgminer I see that the spot where the 7950 used to report is still showing high fan rpms. The thing is that card suddenly has the high 7970 style hashrate and the 7970 in the other slow is reporting a 7950 hash rate lol.
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Offline spincycle

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Re: Cgminer and GPU #
« Reply #5 on: May 12, 2013, 12:28:59 pm »
What the heck.
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Offline JesstersDead

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Re: Cgminer and GPU #
« Reply #6 on: May 12, 2013, 12:38:53 pm »
Now THAT is unusual, to say the least...

You don't run in crossfire mode do you? Also, I have seen some software identify GPU's differently than others on the same install. Precision being one of them. If you are using a single instance of your miner for both cards I would double check to make sure your config flags are still pointing to the correct GPU. If I had this happen on my heterogeneous rig I would suddenly have 7970's being marked at 1792 cores and 7950's having 2048 due to my batch file. Needless to say, hardware errors and driver crashes would be imminent. 

Offline BitJohn

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Re: Cgminer and GPU #
« Reply #7 on: May 12, 2013, 01:01:33 pm »
Im mining the 7950 with the same settings at the moment until the electrician finishes my 5 new 20 amp circuits. Im getting 720 from the 7970's and 550 from the 7950 but its showing wrong running at stable temps etc.... no errors
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