LTC mining with Reaper on a 7970

[#Darren]

Can anyone tell me...

if I rig up 2 7970's on one mother board and "link them", will that be just as effective as having them in separate pc's, or would there be some sort of performance loss?

[W-M]

Can anyone tell me...

if I rig up 2 7970's on one mother board and "link them", will that be just as effective as having them in separate pc's, or would there be some sort of performance loss?

I'm not an expert, but I believe they should be equally effective. In fact, it would be even better for you, because you won't have to pay for the extra electricity for the second motherboard/CPU/etc. I'm not really sure if you have to link them using Crossfire or if the script works on both cards separately, but they should be just as effective of having them in different PC's.

[#Darren]

I'm not really sure if you have to link them using Crossfire or if the script works on both cards separately

hmm good point

I was sort of figuring that with the cards being linked together the script would just automatically use them both, but I may be wrong...

[Vorksholk]

You don't have to put the cards in crossfire
The only detriment to performance with a multi-GPU system is increased heat. If your computers don't ventilate well (small areas, etc.) then two cards in the same place might just be too much heat and cause some throttling. If you have good (air or water or oil) cooling, you should be good to go.

[#Darren]

You don't have to put the cards in crossfire
The only detriment to performance with a multi-GPU system is increased heat. If your computers don't ventilate well (small areas, etc.) then two cards in the same place might just be too much heat and cause some throttling. If you have good (air or water or oil) cooling, you should be good to go.

Nice, thanks    Can you clarify if I can just keep running reaper with the same configuration when I add the second GPU?  Or will I have to make some sort of changes (like running it twice, or changing the concurrency)?

[peacefulmind]

I have pulled my hair out over the last week over 7970s.

See last post here:https://bitcointalk.org/index.php?topic=117221.520

Taco can you take a look at my problem quoted below?

Okay - need some help on this anomaly.

First rig - Sapphire 7970 standard edition with Vapor X, used settings suggested in Taco's thread - out of the box 650k/H per second.

Second rig - two (2x) Sapphire 7970 "GHZ Editions", used exact same settings in Taco's thread - out of the box - only about 350 k/H per second.

I have spent the last week in "newbie purgatory" so have been unable to discuss this issue.  Finally on the second rig, I was able to get 500k/H per second/card by putting aggression back to 13, and overclocking the memory to 1680Mhz.

Can anyone tell me WHY do two of the same brand/manufacturer, same model, have such huge variance in performance?

Why would the two "Ghz editions" VASTLY under-perform the standard one?

Does anyone have any suggestions experience with a Sapphire "GHZ Edition" that could explain the variance?  The standard one was plug and play @ 650k.   The better ones have taken a week of tweaking to even reach 500k/H, and NONE of the recommended settings worked.  I know it is not bad cards because they both perform the same - what is different about the "GHZ editions" that is hurting them so much, and made them so finicky?

First rig is Q6600 65nm, 4GB DDR2, PCI-E 2.0, Win7 Pro 64, Sapphire 7970 - 650kH/s

Second rig is 22nm Quad i5 Ivy Bridge, 8GB DDR3, PCI-E 3.0, Win7 Pro 64, 2 x Sapphire 7970 "GHZ Editions" - 990kH/s (both cards)

I followed all instructions in this thread.  The second rig would only do about 300 per card until I overclocked the RAM on both cards to 1700Mhz and dialed back aggression to 13.  Any variance from that setting and I get LESS than 500kH per card.

I would REALLY like to get the potential out of these supposedly "better" Sapphire 7970 Ghz editions.

[Vorksholk]

You don't have to put the cards in crossfire
The only detriment to performance with a multi-GPU system is increased heat. If your computers don't ventilate well (small areas, etc.) then two cards in the same place might just be too much heat and cause some throttling. If you have good (air or water or oil) cooling, you should be good to go.

Nice, thanks    Can you clarify if I can just keep running reaper with the same configuration when I add the second GPU?  Or will I have to make some sort of changes (like running it twice, or changing the concurrency)?

Yeah, if you used the device 0 setting you will need to add device 1 as well. That's about it for all of that stuff, since they are the same card they should work with the same threadconc.

[#Darren]

You don't have to put the cards in crossfire
The only detriment to performance with a multi-GPU system is increased heat. If your computers don't ventilate well (small areas, etc.) then two cards in the same place might just be too much heat and cause some throttling. If you have good (air or water or oil) cooling, you should be good to go.

Nice, thanks    Can you clarify if I can just keep running reaper with the same configuration when I add the second GPU?  Or will I have to make some sort of changes (like running it twice, or changing the concurrency)?

Yeah, if you used the device 0 setting you will need to add device 1 as well. That's about it for all of that stuff, since they are the same card they should work with the same threadconc.

Thanks again,

are you saying the reaper config file should look like this?

kernel reaper.cl
save_binaries yes
enable_graceful_shutdown no
long_polling yes
device 0
# device 1


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