6990x2 rig fluxuating up and down in hash rate

[Sjalq]

Our new 6990x2 Windows 7x64 rig is fluxuating up and down in hash rate.
Yesterday I was getting 1300+ Mhash/s consistently. Now deepbit is telling me I'm getting 938 Mhash/s.
I'm using GUIMiner poclbcm, default settings (only added -v to the first GPU before the drop)
Clock is at 900Mhz. Mem at 1250. Fan set to keep the chips below 95C.

PS What hash rate should I expect out of this baby?

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[yamato57]

i have 2 6990s and i get 333 per GPU so 333 * 4 = 1332 M/HASH and thats running at 830 core and 625 memory clock.

[BTCBuyer]

Our new 6990x2 Windows 7x64 rig is fluxuating up and down in hash rate.
Yesterday I was getting 1300+ Mhash/s consistently. Now deepbit is telling me I'm getting 938 Mhash/s.
I'm using GUIMiner poclbcm, default settings (only added -v to the first GPU before the drop)
Clock is at 900Mhz. Mem at 1250. Fan set to keep the chips below 95C.

PS What hash rate should I expect out of this baby?

Kiss your cards good bye if you keep them around 90C...

and deepbit calculates your mhash by your shares provided over a certain amount of time. Your cards are really hashing at what ever your GUI says.

[Andeh93]

Kiss your cards good bye if you keep them around 90C...

Nah, not going to kill the cards if they stick at 90C. It's a bit hot, but 95C is the really bad area.

Although I would advise dropping it down to 85C. Depends how consistent the temp is.

And have you trued with other pools? Could have an impact. Test out with slush's quickly just to check.

[Wepp]

I'm getting a very stable rate from my dual 6990's. I saw considerable rate fluctuation until I set CPU affinity to the same for each process.
OC switch turned ON (position 1), and overclocked a little bit further in MSI Afterburner.

http://i.imgur.com/MEiPa.png
http://i.imgur.com/AexEl.png

[Wepp]

I'm also using these flags (all GPUs):

-v -w128 -f60

[pokermon919]

Let me guess that number 2 on MSI is your main card right? I'm pretty sure main card runs hotter than others, I see that anyway with my rig. Just don't oc it as much as the others.

Here's an example with 3 - 5870's:

Main 5870 Core = 905mhz, 85c
Second Card    = 960mhz, 75c
Third Card       = 970mhz, 73c

[Sjalq]

OC Switch, that thing on the MSI motherboard?

[Wepp]

OC Switch, that thing on the MSI motherboard?

Nah, it's a feature of the HD 6990's. They come with a switch that raises the voltage slightly and increases the core clock from 830mhz to 880mhz.

[Wepp]

Let me guess that number 2 on MSI is your main card right? I'm pretty sure main card runs hotter than others, I see that anyway with my rig. Just don't oc it as much as the others.

Yep. For some reason, MSI Afterburner shows it as GPU #2, but in GUIMiner, it shows up as GPU #0. *shrug*

It does run a little hotter than the others. Probably due to position of the GPU in relation to the airflow in the box (it's at the top nearest the exhaust).

[Sjalq]

i have 2 6990s and i get 333 per GPU so 333 * 4 = 1332 M/HASH and thats running at 830 core and 625 memory clock.

What temperature are you running?

[Sjalq]

Well the stability definitely has something to do with the fan speed/heat. Allowing it to run hotter solves the instability fluctuation.

How do I access that switch. My Club3d cards don't have one on the outside (that I can see while they are plugged in) and there is no manual to speak of in the box??