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Other => CPU/GPU Bitcoin mining hardware => Topic started by: pandemic on July 08, 2011, 01:53:30 PM



Title: to crossfire or not to crossfire
Post by: pandemic on July 08, 2011, 01:53:30 PM
Is it better to run two 5830's in crossfire mode or individually?


Title: Re: to crossfire or not to crossfire
Post by: MiningBuddy on July 08, 2011, 01:54:45 PM
Individually.


Title: Re: to crossfire or not to crossfire
Post by: Trini8ed on July 08, 2011, 02:44:37 PM
Don't do crossfire bottlenecks the cards and if you have issues with windows make a vga dummy plug which all you need is a dvi to vga and a couple of resisters to get it working and it makes windows see the card.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html



Title: Re: to crossfire or not to crossfire
Post by: pandemic on July 09, 2011, 02:14:41 AM
Don't do crossfire bottlenecks the cards and if you have issues with windows make a vga dummy plug which all you need is a dvi to vga and a couple of resisters to get it working and it makes windows see the card.

http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html



Yeah, just found out about that last night. I think CCC 11.7 doesn't need dummies though. May try that. I have a 4870 and 5830 in there now. Eventually I'll get 2x5830's. :D


Title: Re: to crossfire or not to crossfire
Post by: FreeJAC on July 09, 2011, 02:44:49 AM
can you confirm in 11.7 indeed no longer needs dummy plugs?


Title: Re: to crossfire or not to crossfire
Post by: Jack of Diamonds on July 09, 2011, 05:43:10 AM
can you confirm in 11.7 indeed no longer needs dummy plugs?

Worked on all of my multi-gpu rigs. No more hassle with monitor cables and dummies.


Title: Re: to crossfire or not to crossfire
Post by: pandemic on August 05, 2011, 02:19:02 AM
I see a lot of respectable rigs all using crossfire. I'm currently using 2x5830's right now at 307mh/s a piece. I can't imagine beating that just by using crossfire but wanted to check anyway.


Title: Re: to crossfire or not to crossfire
Post by: Swishercutter on August 05, 2011, 05:36:30 AM
can you confirm in 11.7 indeed no longer needs dummy plugs?

Worked on all of my multi-gpu rigs. No more hassle with monitor cables and dummies.

I just put a 5th card in my rigs last night with 11.7 and I also did not need the dummy plugs...OC through AOCLBF.  I read somewhere that you could not software OC without the dummys but it seems to be working for me.


Title: Re: to crossfire or not to crossfire
Post by: pandemic on August 05, 2011, 02:21:24 PM
can you confirm in 11.7 indeed no longer needs dummy plugs?

Worked on all of my multi-gpu rigs. No more hassle with monitor cables and dummies.

I just put a 5th card in my rigs last night with 11.7 and I also did not need the dummy plugs...OC through AOCLBF.  I read somewhere that you could not software OC without the dummys but it seems to be working for me.


No doubt, that's working fine for me too. I'm just thinking about trying crossfire to see if I can exceed 614mh/s. I don't think I will but wanted to get opinions.


Title: Re: to crossfire or not to crossfire
Post by: cicada on August 05, 2011, 07:44:39 PM
No doubt, that's working fine for me too. I'm just thinking about trying crossfire to see if I can exceed 614mh/s. I don't think I will but wanted to get opinions.

I'm not sure what you're reading, but everything that I've seen shows crossfire hurts performance.  Miners using crossfire are either leaving value on the table, or they're also using their rigs for gaming where crossfire is worthwhile.

Your cards will hash faster isolated.


Title: Re: to crossfire or not to crossfire
Post by: pandemic on August 06, 2011, 05:19:05 AM
No doubt, that's working fine for me too. I'm just thinking about trying crossfire to see if I can exceed 614mh/s. I don't think I will but wanted to get opinions.

I'm not sure what you're reading, but everything that I've seen shows crossfire hurts performance.  Miners using crossfire are either leaving value on the table, or they're also using their rigs for gaming where crossfire is worthwhile.

Your cards will hash faster isolated.

Sounds good. I've just seen a lot of high performance rigs selling WITH crossfire cables on. (ie looking at the photos)



Title: Re: to crossfire or not to crossfire
Post by: mikeo on August 06, 2011, 11:32:37 PM
Just added a second 5830 to my gaming/miner rig. In CrossFireX running Linuxcoin, 900/300 overclock the primary card has a stable 312 MH/s rate and the secondary card fluctuates from 310 MH/s down to 280 MH/s and back up again. So I see what is meant by losing efficiency. Games nice though.


Title: Re: to crossfire or not to crossfire
Post by: PcChip on August 07, 2011, 02:04:29 AM
I don't want to use dummy plugs since I lose 3-5 MH/s per dummy plug, so I crossfired a pair of 5770's yesterday.  Now, I can access both DEVICE=0 and DEVICE=1 with no monitors attached (TightVNC), and the pair are hashing along at 220 MH/s each. 

I don't see any wasted performance ... ?


Title: Re: to crossfire or not to crossfire
Post by: RandyFolds on August 07, 2011, 10:19:42 PM
I don't want to use dummy plugs since I lose 3-5 MH/s per dummy plug, so I crossfired a pair of 5770's yesterday.  Now, I can access both DEVICE=0 and DEVICE=1 with no monitors attached (TightVNC), and the pair are hashing along at 220 MH/s each. 

I don't see any wasted performance ... ?

I run 3x6970 crossfired with no performance issues. Better than dicking with two non-existant monitors.


Title: Re: to crossfire or not to crossfire
Post by: PcChip on August 08, 2011, 04:35:45 PM
Since I use TightVNC I have never had to "dick with monitor settings", on my other rigs I just walk into the room and physically plug a monitor into the card I want to spin up, then go back to my PC and remotely start the mining shortcut (I've been using shortcuts lately instead of batch files), then go back to the rig and swap the monitor to the next card, and so on.