Bitcoin Forum

This was going to be my original post:

"I have been trying to get two cards to work independently with some success but the mining rate doesn't seem nominal when both are on.It is a Radeon 5770[primary card] and Radeon 6950[dummy plug] using a Corsair TX650w PSU.I have read the boards about the 100% CPU issue but don't know if that is the issue or PSU limitations.



1.Using either the Juniper[Primary card] or Cayman[dummy plug] alone results in one of my CPU cores being fully stressed @ 25%......but the mining rates are normal @ ~195 for the Juniper and ~325 for the Cayman,stock.

2.When trying to use both cards at the same time however,the following is the result.
http://img714.imageshack.us/img714/293/miningrateprob.jpg"
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Now,After doing some tinkering for the last few hours,I have now gotten this issue fully resolved by simply uninstalling the newest Catalyst 11.7 WHQL drivers.It is NOT the newest APP 2.5 runtime as some have mentioned that is still very stable with the Catalyst 11.6B drivers which I highly suggest under XP if you have a Multi-GPU configuration.The 100% CPU or core utilization PCBLM bug was that debilitating to hash rates and made me almost buy another PSU.

I guess the moral of the story is:"When in doubt try everything,before buying anything" and hopefully this helped some of you whom have similar issues.I also highly suggest getting a driver cleaner of sorts like Driver sweeper or Driver cleaner pro after every uninstall of Catalyst drivers to isolate the issue.



                                                                                                                                                                       Cheers

Yes indeed, 100% agreed with you there.  I have a similar situation on one of my rigs (6970 main & 6770 with dummy plug).  With 11.7 I had the same exact problem; I went back to 11.6 and it's running like clockwork. :)

i as well had to return to 11.6. same thing.