Bitcoin Forum

I have 2 rigs running 3 5970's each. They run great.

 I have tried (many, many times) to get the fourth running and cant quite get there. Windows installs and recognizes all 8 GPUs, even the miners (guiminer poclbm, phoenix miner, and cgminer) recognize all 8 adapters. The problem is that the miners either hang (phoenix and cgminer) or only start mining on 3 cores (poclbm).

Anyone who has succesfully run 8 GPUs I would love to know what os, drivers, and miners you used in your rig.

Thanks.

Need much more info on your hardware. Sounds like a power supply problem to me!

I dont think its a power issue. Im running 3400 watts, total. 4 x 850 watt seasonics - 1 power supply for every two cards.

Well shit we can rule out the Power Supplies  ;D

As for the problem I'm not sure. I remember seeing a similar issue in a post here one time but I can't find it. I would say try a linux live cd and see if it works on linux. If it does I might suggest to just put linux on your machine.

Take a look at the interrupts, everything fine there?

Linux won't let you overclock the cards.. Windows should work, what mobo is it? I had similar issues on some of my rigs while trying to add the 3rd card. I had to remove all the cards, and install only the new card. I then reinstalled the drivers, made sure the card was running correctly and added the other cards. I don't really what the deal was, but I've had to do that on a couple rigs.

I never got 4x5970s running in Windows 7.  Tried optimizing bios (turning off everything not needed), clean install, tried 2 different MB.  No dice.

It would BSOD on installing drivers on 1 MB.  Trying 6 GPU worked, and mined fine.  Adding two GPU worked, rebooted, still good tried to mine and hardlock and/or "AMD display driver stopped responding".  On the second motherboard it wouldn't even install windows w/ 8 GPU installed.  Got to the point where it reboots for first time and hardlocked BSOD. 

I tried countless combinations of drivers versions (w/ SDK runtime seperate), also tried not installing any drivers first and installing all updates & SP and then drivers.  Tried preventing it from installing any system drivers to get AMD driver in first and then other drivers.   Nothing.

Not saying it is impossible but 8 GPU wouldn't work for me.  7 GPU worked fine though.  I grabbed a spare 5870.  3x5970s + 1 x5870 worked but 4x5970s didn't.

I finally got it working in Linux (another long process).  I think you mistyped linux is fine for overclocking you just can't overvolt.   So likely I am looking at a BIOS flash to raise the core voltage.

https://bitcointalk.org/index.php?topic=66606.msg773184;topicseen#new

I have a few machines going with four 5970. I had to re-install my display drivers and sometimes my OS to get all the cores going but everything has been working well.