Erratic voltage drops?

[Bengel]

Hey guys!

Just put together another mining rig and ran into a little issue. I got everything setup and running and started to test mining on one GPU when I encountered this (Check the 12V, VDDC and VDDC Current sections)

http://gpuz.techpowerup.com/11/07/27/gsp.png

This came with an erratic hashrate and the GPU load never hit 99%. I'm running this machine with 3x6950s with a 1000w PSU and was only attempting to hash on the first card. I had a kill-a-watt plugged in at the time, and the draw from the wall fluctuated from 279-282 watts which seemed fairly normal.

Has anyone encountered this? Or is this just a shoddy PSU?

[1715178432]

1715178432

[Jazkal]

Couple of questions:

1) What PSU?

2) How many video cards? And models?

[Jack of Diamonds]

Knew right from the title you had 69xx cards running..

Go to catalyst control center, write 'overdrive' in the search field and disable PowerTune by setting the slider to 20 on each GPU.

Otherwise the card will constantly throttle down and go back up in an attempt to 'save power' (a mechanism which might work for gaming but is useless for mining as you want constant peak performance)

[Bengel]

Couple of questions:

1) What PSU?

2) How many video cards? And models?

1) Rosewill BRONZE Series RBR1000-M 1000W

2) 3x PowerColor AX6950 1GB

Knew right from the title you had 69xx cards running..

Go to catalyst control center, write 'overdrive' in the search field and disable PowerTune by setting the slider to 20 on each GPU.

Otherwise the card will constantly throttle down and go back up in an attempt to 'save power' (a mechanism which might work for gaming but is useless for mining as you want constant peak performance)

Why does it always seem that the 69xx cards have weird issues! Underclocking in Linux, Opening GPU-Z while using the OpenCL miner hard locking windows, and now this! I'll give this a shot when I go on my lunch break. Thanks!

[Bengel]

Well I tried jacking the PowerTune settings to 20 and it seemed to quell the problem, but not entirely remove it. The voltage drops are still there, but much less frequent. I'll play around a bit tonight and see what I find out.

[Jack of Diamonds]

Try 'force constant voltage' (settings tab) in Afterburner & set PowerTune slider to 20.

[Bengel]

Just tried that... No go.

I tried installing the 11.7 drivers and see what happened. Good news! Now when I start the miner the temperature shoots from 40c to 80c in literally 4 seconds. I clicked stop there... I'm afraid to let it go. Temps were confirmed in CCC/GPU-Z and MSI Afterburner?! The fan goes from quiet to 100% in that time frame as well.

I'm so confused... Im burning the whole thing down and starting from scratch with a fresh Win 7 install.

[mikeo]

Don't know if this is a problem for you but I'm having stability issues with a 4xGPU setup. See this post:
http://forum.bitcoin.org/index.php?topic=32694.msg408396#msg408396

You may want to check your voltage at the wall outlet. Mine was only 108V.