2x 7970s not mining at same rate

[Herp-a-derp]

I have a very strange problem which is probably related to being a n00b, so forgive me in advance.

There are 2x 7970 Sapphire Vapor-X in one rig, both have identical overclocks and Crossfire is disabled (but cable in place). However one card hashes at twice the speed of the other.



CCC version 13.1 plus most recent APP version (2.8 iirc).

Can some advise what I am doing wrong please, it is driving me insane.

Thanks

[1715140633]

1715140633

[1715140633]

1715140633

[HellDiverUK]

Well the ancient version of cgminer you're using probably isn't helping.  Try 3.1 which has 7970 fixes.

[Frizz23]

There are 2x 7970 Sapphire Vapor-X in one rig, both have identical overclocks ...

What's your core, mem and voltage?

[ssateneth]

i want to know this too. your 800 mhash is crazy

[melmo]

i want to know this too. your 800 mhash is crazy

Damn, I want 800 mhash from my Sapphire!  I think I'd have to overclock it up to 1300MHz, maybe if I was watercooling...

[-ck]

7970s get 0.6MH per Mhz of clock speed, so you can figure it out.
Some really lousy applications (I'm looking at you, flash) fix your GPU clock speed to a particular value for video synchronisation and closing your browser or disabling acceleration in video playback for your porn will fix it. Checking the clock speed that it's actually currently at (in cgminer GPU menu) is a giveaway that you have you this issue.

[Herp-a-derp]

I have a very strange problem which is probably related to being a n00b, so forgive me in advance.

There are 2x 7970 Sapphire Vapor-X in one rig, both have identical overclocks and Crossfire is disabled (but cable in place). However one card hashes at twice the speed of the other.



CCC version 13.1 plus most recent APP version (2.8 iirc).

Can some advise what I am doing wrong please, it is driving me insane.

Thanks

Here we go:

1. remove the better card from your system
2. change the slot for the "bad" card, make sure it is set properly in the slot
3. use the same number of threads as you used for the "good" card
4. use msi afterburner to set the clocks and voltage
5. gpu-z sensor to check the settings from 4)
6. start cgminer with I:9
7. don't play video games while you mine
8. put the "good" card in
9.  If all above does not work, change the motherboard, rinse and repeat  

your version of cgminer is fine.

Thanks. Swapped the cards and totally removed crossfire cable and it's back to full speed. Although the same thing just happend to a different rig  
One question: Is I9 better for 7970s?

There are 2x 7970 Sapphire Vapor-X in one rig, both have identical overclocks ...

What's your core, mem and voltage?

Core: 1350, Mem: 1400, V: +10% All done through CCC.
For those interested: Stock fans replaced due to failure with 8cm case fans, which seem to work bettter for me. Room temp is steady 18 degrees C. Cards run 75-80 degrees C.