6950 issue

[tarrant_01]

I have had 2 6950's running for a few months on one machine for a while now and this last week I've noticed that one of the cards is putting out less than the other.  It's doing about 220 vs the 350 of the other one.  I still have the old drivers and old sdk.  Using the updated guiminer.  That might be the issue.  That's the only thing that's changed in the setup although on another machine, also running 2 6950's, I dont have this low output.

Thoughts/suggestions?

[tarrant_01]

Well I restarted and now it's outperforming the other card so who knows.

[kpriess]

Are you running them in xfire..?

[tarrant_01]

It seems like the other card is slacking now.  Yea, they have xfire enabled but it's never made a difference until recently.

[kpriess]

I remember after using a certain version of drivers/SDK with a combination of flags [sorry, this was a long time ago, don't remember any specifics] my hashing power would be split up between both cards, I had clean the drivers I had and start installing from zero..

[tarrant_01]

I switched to cgminer and the hashrates are as expected at intensity 9. But it get's up to 100C really fast. This is with a box fan blowing into the case and the fan speed at a reported 100%. So, I put the intensity down to 5 for now as temps are more reasonable there. I am going to clean it later today and see if that helps.

In cgminer the RPM for the fan speed goes up in the ten thousands for a few seconds then normalizes. I might have fans going out.

[antares]

have you watched the temps of the card? we just figured while we tried to kill a 6950 that it still ran stable even without fans, but it seemed to automatically clock down to handle the head. so without fans, the 6950 did about 100mh/s, just to keep running below 110 C

[tarrant_01]

Yea I've been watching the temps and it was climbing up to 105 a bit ago. I now have it running at 800mhz(from 870 stock) and at intensity 0 to keep it at 85C.  It's doing about 250Mhash/s now, better than nothing.

Is it possible to get replacement fans? I see there's a 3 year warranty on parts but they technically haven't gone out yet. I'd really rather just buy the fan and put them on myself. Perhaps I should put new grease on it? I've never taken a card apart before but I can give it a shot.

These are what I am using: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125385

I don't want to kill it. I don't want to come home to burnt up computer and house smelling like smoke either. I am trying to prevent that

[mikethebodacious]

I get about 360Mh/S on each of my 6950s with 65% fan and under 70C so your temps seem extremely excessive.  Do you downclock your memory?  You can downclock to 250-300MHz  on 6950s and still be stable 24/7.

[tarrant_01]

I'm still not sure what was going on with it.  I cleaned it again and now it's within range of the other card on the same machine.  I wasn't downclocking memory at the time either but I am now.  I'm running 880/765...these cards will only let me keep the memory within 115MHz less than the engine speed.  If I try to clock lower it just resets to default 1250.

I do have an RMA open with Gigabyte, but I am probably going to close it.  The case these cards are in too seems to be part of the issue as well and I am working on a solution to that.  This particular case stays around 80C and the other 65C.

Keep in mind these are the cards that can't have the BIOS overwritten to have the shaders unlocked (I tried a few times).  They have that laser-cut or whatever, I can't remember the term.

[mikethebodacious]

If you have poor airflow in your case I would highly recommend getting a few of these for your case:

http://www.newegg.com/Product/Product.aspx?Item=N82E16835185060

You could go for the slightly slower RPM models as well to cut down on the dBA but the air flow from these fans is just amazing, that and your video card's dBA is probably around ~35 dBA anyways.  I would put 2 on the left side of the case to blow cool air directly on the cards, with your 3 fan design video cards that would be ideal.

As for your memory clock I would recommend using Afterburner.  To downclock the memory you have to lower the memory then close and reopen Afterburner to keep downclocking it to lower speeds.  880MHz speed with 250MHz memory should get you lower temps and much lower power consumption, at this point in the mining game the less watts consumed the more profit    Screw unlocked shaders, all that does is up your power consumption anyways!

[tarrant_01]

I've always had a box fan lined up with the case so hot air is coming out both sides and it's seemed to always do the trick up until now.  I'll give afterburner a shot for the memory thanks for that suggestion.  I have moved everything now to an open case and it's revealed to me the issue.  The fans on that card are off when the card is idle and 1 always works, 1 sometimes works with motivation, and the other tries to work but can't.  Printing my shipping label tomorrow and sending it out!  Kinda sad though that I'll be short a card  

I've even gotten video of cgminer and the fans all in action....coming soon!

Edit: I remember trying to download and use afterburner last year.  I remember it only installing something that wanted to work via a mobile fun. It was confusing as hell too.  I am trying it again right now.

Edit #2: Afterburner is running and the memory slider goes down to 625, but setting it there makes the memory clock speed the default 1250...so no go.

[mikethebodacious]

You have to edit the afterburner.cfg file to overclock/underclock, Afterburner isn't retaining the downclock overclock info because you need to enable unnoficial overclocking.  Here are the directions how:

http://forums.guru3d.com/showthread.php?t=338906

If you're on Windows and it's causing system crashes you may also need to edit your registry by setting "EnableULPS" to 1.

[sergio]

if is being slowed down due to heat, the card will automatically slow down to prevent destruction of the card itself, but even then it could get destroyed if the temperature is around 100C.

It happened to me a fan died and the card temp was around 97C to 103C, and  the miner ran very slow, water cooling the cards makes the temperatures drop to about half, and less if the water is kept cold

Do not run your card near 100C it is dangerous to the card.

[tarrant_01]

The card just doesn't want to go below 115 difference at 880Mhz. At 900 it'll let me do 125 but thats it.  I made those changes to AB too and now it won't change the clocks at all :/  not a big deal.

I sent the problem 6950 to Gigabyte today also.  Going to change the title.

[tarrant_01]

Ok.  RMA'd the card and they sent me a new one back.  As soon as I run cgminer it's at 90C and the other older card is at 60C.  I thought maybe the sound card next to it might be causing a temperature issue so I took it out and it's at 92C right now.  Clocks are 880/765.  Any ideas?  This is on an open air case.

edit:  Swapped the cards around and still getting 90C on the new card.