dual 6870 on 12.04 LTS - any gotchas or advice? (and 2 easy questions)

[bitcoinnix]

Right now I'm running a single 6870 at stock speeds (900/1050) @ intensity 17 and getting about 290 kH/s sustained at 69C in Xubuntu 12.04 LTS with the 2.4SDK and 2.6 driver.

I've got a 2nd 6870 waiting to go in - have to wait on a bigger PSU.  2 questions about this upcoming upgrade:
1.  Are the gains of a 2nd adapter usually 2x or some smaller percentage, like +75% so far as hash rate goes? 
2.  Do I need the crossfire adapter or do I run these independently?  I've never had more than one GPU before...

Anyone got any advice for optimizations or gotchas I should be aware of for this configuration?

Thanks!

[1714814094]

1714814094

[kpriess]

Right now I'm running a single 6870 at stock speeds (900/1050) @ intensity 17 and getting about 290 kH/s sustained at 69C in Xubuntu 12.04 LTS with the 2.4SDK and 2.6 driver.

I've got a 2nd 6870 waiting to go in - have to wait on a bigger PSU.  2 questions about this upcoming upgrade:
1.  Are the gains of a 2nd adapter usually 2x or some smaller percentage, like +75% so far as hash rate goes? 
2.  Do I need the crossfire adapter or do I run these independently?  I've never had more than one GPU before...

Anyone got any advice for optimizations or gotchas I should be aware of for this configuration?

Thanks!

You could probably hash at ~275-325 with the right flags..

You can run all the cards your system can take without penalty as long as you DO NOT cross/triple/etc-fire them, run them independently with VGA plugs, that's how I had my 4 6870s mining back in the time I had them..

[bitcoinnix]

Right now I'm running a single 6870 at stock speeds (900/1050) @ intensity 17 and getting about 290 kH/s sustained at 69C in Xubuntu 12.04 LTS with the 2.4SDK and 2.6 driver.

I've got a 2nd 6870 waiting to go in - have to wait on a bigger PSU.  2 questions about this upcoming upgrade:
1.  Are the gains of a 2nd adapter usually 2x or some smaller percentage, like +75% so far as hash rate goes? 
2.  Do I need the crossfire adapter or do I run these independently?  I've never had more than one GPU before...

Anyone got any advice for optimizations or gotchas I should be aware of for this configuration?

Thanks!

You could probably hash at ~275-325 with the right flags..

You can run all the cards your system can take without penalty as long as you DO NOT cross/triple/etc-fire them, run them independently with VGA plugs, that's how I had my 4 6870s mining back in the time I had them..

Thanks man - never heard of the VGA plug thing before! 

[kpriess]

Right now I'm running a single 6870 at stock speeds (900/1050) @ intensity 17 and getting about 290 kH/s sustained at 69C in Xubuntu 12.04 LTS with the 2.4SDK and 2.6 driver.

I've got a 2nd 6870 waiting to go in - have to wait on a bigger PSU.  2 questions about this upcoming upgrade:
1.  Are the gains of a 2nd adapter usually 2x or some smaller percentage, like +75% so far as hash rate goes? 
2.  Do I need the crossfire adapter or do I run these independently?  I've never had more than one GPU before...

Anyone got any advice for optimizations or gotchas I should be aware of for this configuration?

Thanks!

You could probably hash at ~275-325 with the right flags..

You can run all the cards your system can take without penalty as long as you DO NOT cross/triple/etc-fire them, run them independently with VGA plugs, that's how I had my 4 6870s mining back in the time I had them..

Thanks man - never heard of the VGA plug thing before! 

They're easy to make, just 3 resistors on a DVI2VGA adapter and you're set.. Plenty of DIYs out there..