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Topic: [Reaper - Litecoin] Varied hash rates among different 7970s, why? (Read 1877 times)

newbie
Activity: 8
Merit: 0
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?

What did you end up doing with this? Did you flash bios?
member
Activity: 84
Merit: 10
My guess would the core/mem clock rate, try using a software utility like Sapphire Trixx to lower the clocks to what the other card is set to and see what your performance is like.
newbie
Activity: 20
Merit: 0
Try flashing the bios to the standard edition. Let me know how it goes.
full member
Activity: 196
Merit: 100
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?
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