One of my HD 6870's is getting way less Kh/s than the other.

[sublime5447]

Can anyone help me? 

One of my rigs has two Radeon HD6870 core edition 1 GB DDR5 XFX graphics cards in it.

Cgminer says GPU 0: 69.0C 75% 275.1/276.2 Kh/s A:54 R:0 HW:0 U:876/m I:15

but GPU 1 is only getting

GPU 1: 33.0C 36% 30.5/30.8 Kh/s A:11 R:0 HW:0 U:1.27/m I:15

I tried changing the configuration settings around but GPU1 is always way behind. I had it working correctly last week and I don't know what changed.  It doesn't make since to me because they are the exact same card.  Nothing seems to be wrong with the hardware itself.  People have told me that it has to be a problem with the software. 

Any help will be greatly appreciated.   

[GernMiester]

I had this type issue with crossfire enabled on my 6870's. I turned it off and they hash the same now

[Viceroy]

Do the GPU fans actually spin?  Any chance one is intermittent or dead?

[Joe_Bauers]

Are they on riser cables?  I've had cables go bad which caused a sudden drop in Kh/s on the card. Obviously could also be the card going bad.

[sublime5447]

I enabled the cross fire and they started hashing away thanks for the help

[Viceroy]

You do not need to enable crossfire.  I run 6870x2's...



 cgminer version 2.11.3 - Started: [2013-03-31 12:22:58]
--------------------------------------------------------------------------------
 (5s):532.1M (avg):529.1Mh/s | A:9770  R:26  HW:0  U:7.4/m  WU:7.4/m
 ST: 2  SS: 0  NB: 203  LW: 13850  GF: 2  RF: 0
 Connected to mine.mtred.com diff 1 with stratum as user mmjtip_00002
 Block: 0144882bf2a5e2ac...  Diff:6.7M  Started: [10:18:13]  Best share: 14.3K
--------------------------------------------------------------------------------
 [P]ool management [G]PU management ettings [D]isplay options [Q]uit
 GPU 0:  87.0C 327405RPM | 252.3M/250.8Mh/s | A:4573 R:15 HW:0 U:3.47/m I: 4
 GPU 1:  98.0C 100%    | 280.1M/278.4Mh/s | A:5197 R:11 HW:0 U:3.95/m I: 4


$ aticonfig --lscs
    Candidate Combination:
    Master: 0:0:0
    Slave: 0:0:0
    CrossFire is disabled on current device
    CrossFire Diagnostics:
    CrossFire can work with P2P mapping through GART
    Candidate Combination:
    Master: 0:0:0
    Slave: 0:0:0
    CrossFire is disabled on current device
    CrossFire Diagnostics:
    CrossFire can work with P2P mapping through GART

[altoz]

I had this same problem. If you're using windows and you have on-board video, try connecting one of the ports on all of the cards. You can also put in a "dummy plug". Basically, the problem might be that Windows doesn't think the gpu is there since nothing is connected to it.