I had this happen on Xubuntu with 2 cards. What worked for me was using a dummy plug. I only needed 1 dummy plug to make both of the cards get their full hash rate.
If you don't have a dummy plug handy, try this:
Stop cgminer
Plug in a monitor
Start cgminer
Try that with each of the DVI outputs. For me, having the monitor (or dummy plug) in card 0 in the top slot worked.
Topic: two identical machines - substantially different hash - Why? (Read 2020 times)
Have you tried swapping the cards between the machines, might have a bad MB.
You may be right, or a badly seated card....
Code:
two GPU's, Card A
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[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: | 283.5M/300.8Mh/s | A:2 R:0 HW:0 U: 3.40/m I: 5
GPU 1: | 283.7M/300.7Mh/s | A:1 R:0 HW:0 U: 1.70/m I: 5
GPU 2: | OFF / 0.000h/s | A:0 R:0 HW:0 U: 0.00/m I: 5
GPU 3: | OFF / 0.000h/s | A:0 R:0 HW:0 U: 0.00/m I: 5
--------------------------------------------------------------------------------
two GPU's, Card B
--------------------------------------------------------------------------------
[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: | OFF /2.487Mh/s | A:0 R:0 HW:0 U:0.00/m I: 5
GPU 1: | OFF / 0.000h/s | A:0 R:0 HW:0 U:0.00/m I: 5
GPU 2: | 95.80M/34.02Mh/s | A:0 R:0 HW:0 U:0.00/m I: 5
GPU 3: | 86.04M/31.47Mh/s | A:0 R:0 HW:0 U:0.00/m I: 5
--------------------------------------------------------------------------------
Have you tried swapping the cards between the machines, might have a bad MB.
What could cause two identical machines to display substantially different hash rates?
1) cgminer/Drivers/OS/Hardware are Identical
2) Temperatures are fine, and lower on the slower machine.
3) Machines are not overclocked or under-clocked
4) The machine with only two cards is running slower
Working:
Broken:
1) cgminer/Drivers/OS/Hardware are Identical
2) Temperatures are fine, and lower on the slower machine.
3) Machines are not overclocked or under-clocked
4) The machine with only two cards is running slower
Working:
Code:
--------------------------------------------------------------------------------
[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: | 257.6M/210.0Mh/s | A:4 R:0 HW:0 U: 1.94/m I: 9
GPU 1: | 241.3M/209.1Mh/s | A:7 R:0 HW:0 U: 3.40/m I: 9
GPU 2: | 245.5M/211.0Mh/s | A:5 R:0 HW:0 U: 2.43/m I: 9
GPU 3: | 238.9M/209.7Mh/s | A:4 R:1 HW:0 U: 1.94/m I: 9
Broken:
Code:
--------------------------------------------------------------------------------
[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: | 26.30M/42.08Mh/s | A:1 R:0 HW:0 U: 0.70/m I: 9
GPU 1: | 26.28M/42.67Mh/s | A:0 R:0 HW:0 U: 0.00/m I: 9
GPU 2: | 26.08M/42.47Mh/s | A:1 R:0 HW:0 U: 0.70/m I: 9
GPU 3: | 26.05M/38.76Mh/s | A:0 R:0 HW:0 U: 0.00/m I: 9
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