Bitcoin Forum

Preface info:
MSI 890FXA-GD70 - motherboard with room for four double-wide GPU
Athlon II X2
2GB DDR3
Caviar black HDD
Four Radeon 6870
PSU: Corsair HX1000 and Ultra X3 1000W (testing both)
Windows 7 64bit / Windows 7 32 bit (both tested)
Catalyst 11.4
Clean install of windows, installed drivers, and mining software
Note: i have another computer identical to this. I bought enough to build two identical machines

Problem:
To get all 4 GPUs working, I have to Crossfire GPU1 and GPU2, GPU3/4 are dummy plugged

I can start mining on all 4 GPUs and it works like a charm at 1.1Gh/s just like the other rig. This one after ~10 minutes or so, GPU1 and GPU2 will have a problem
"Problem connecting to bitcoin RPC" is what I get under GUIminer
poclbm , the first two clients just lock up. The last two clients keep going
diablominer: mines on all 4 GPUs for about 10 minutes then drivers crash, then runs at half speed
rpcminer-openCL: I can only get it working on two GPUs


I swapped cards into different order, and its still the cards in PCIE 1 and PCIE 2 that fail first

I swapped around the PSUs, reinstalled windows, re-did drivers. I'm thinking this might be a motherboard problem now, but I don't know what to test.. What do you guys suggest?

Try removing one of your cards entirely and see if it is stable like that.

I've had problems trying to run 4 6950's and pulling one card stabilized it completely.  I'm wondering if you are seeing a similar problem.

Jere

Doing this now. Pulled one card, seeing how it goes.

Nope. First two GPU's again, stopped mining.

I've seen you post in other threads saying that you couldn't get 4 cards to work at all.  Is this the same setup?  Is GPU-Z working for you now?

What did you do to fix that?

Jere

I've been having a lot of problems getting 4 GPUs working

I got all 4 to run by putting GPU's 1 and 2 in crossfire mode with a bridge. Suggestion by another forum post, and it worked. poclbm worked

I thought I was having this problem only on one computer, but I got the "connection problem" on my other dedicated miner that was identical, but it had been mining stable for 48 hours (although no GPU driver crash. just GUI miner for now)... I don't get why this is happening.

I've never seen the error before and its causing havoc lol

Most excellent.  I just bridged 1 and 2, enabled crossfire on those two, then plugged in 4 and I'm now mining on all 4 cards.

Only 2 odd things:

• MSI Afterburner won't start due to "Unable to initialize driver wrapper" so I can't overclock as much (I can only go to 840)
• The hash rates of the bridged GPUs is very unstable.  they bounce between 250 Mhash/s and 315 Mhash/s

That said, I'm extremely happy to not have a $250 card laying at the bottom of my case doing nothing. :)

Thanks!
Jere

Yeah, well are you getting any weird connection issues? What mining client you using?

Can you say which pool/pools you connecting?

deepbit.net

Slushes Pool having the same problem.

"Connection Problems" On and off usually always says Connection Problems.