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Poor 7950 Crossfire OC

RichH

RichH

RichH

Associate
Joined
1 Dec 2011
Posts
434
Hi Guys,

I have 2 x 7950, 1 Windforce and Saphire OC.

On it's own the Windforce OCs brilliantly - 1200/1600 @ 1.2v. It might even go higher but I havn't unlocked it in MSI.

In crossfire however I can't even get to 1Ghz. 975Mhz seem to be the highest I can manage. The strange thing is I can get 975 on stock volts, but can't get any higher even with 1.25v.

Initially I thought the second card was just a poor clocker, but it doesn't make sense that i cant clock higher even with a significant voltage bump.

Am i doing something wrong?
 
have you tried swapping them over or running them further apart (if you can)?

both those cards will be dumping heat inside the case and if the way the airflow works is that one card is just sucking in all the heat from the other one or there's not enough space to draw clean air then yeah they will be sucking the life out of each other
 
I don't think heat is a problem. The overclock fails within seconds of loading the cards, while they are still both cool.
 
it should, 7950's should be under 200w each stock and maybe 250w each overclocked at a guess - 100-150w for OC'd CPU plus other bits, 700-750w at the most I would have thought... not sure if OCZ PSU's still have the problems they used to

I've got an AX850w running 2 670's with big OC's and a 3930k at 4.5ghz and watercooling pump, 16 fans 2TB drives etc. with absolutely no probs
 
That is what i thought. Didn't know OCZ PSUs had problems though.

Perhaps I will take out the 1st card and see what the max OC is on the second card on it's own before jumping to any conclusions about broken PSUs.
 
RichH said:
but it doesn't make sense that i cant clock higher even with a significant voltage bump.
Click to expand...

Extra voltage is for when the core can go higher.

If the core is at it's limit, then that's it, if it's unstable@950MHz(for talking sake), it doesn't matter how much voltage you throw at it, it won't budge any higher.

RichH said:
Perhaps I will take out the 1st card and see what the max OC is on the second card on it's own before jumping to any conclusions about broken PSUs.
Click to expand...

That's what you should have done in the first place.:)

Remove the WF from the system completely and find the limit of the Sapphire.

Even if they both hit 1200MHz seperately, it doesn't mean they will as a pair.

When overclocking with dual cards, it's best keeping your cpu@stock until you find comfortable limits, it can be a combination of system overclocking instability which causes ctd.

As it's a dual setup, it's also best to come back down from your max clocks for stability reasons, it will help with ctd's.
 
tommybhoy said:
Extra voltage is for when the core can go higher.

If the core is at it's limit, then that's it, if it's unstable@950MHz(for talking sake), it doesn't matter how much voltage you throw at it, it won't budge any higher.
Click to expand...
Ah right, I didn't realize this.
That's what you should have done in the first place.:)
Click to expand...
I know, have been too lazy though!
As it's a dual setup, it's also best to come back down from your max clocks for stability reasons, it will help with ctd's.
Click to expand...
You mean come down from max GPU clocks? I was expecting to have to come down from max clocks, but will be a bit miffed if I have to run at pretty much stock.
ctd's
Click to expand...
Sorry what does this mean?
 
RichH said:
You mean come down from max GPU clocks? I was expecting to have to come down from max clocks, but will be a bit miffed if I have to run at pretty much stock.
Click to expand...

Yes, if the sapphire limits out@1100MHz and the WF does 1200MHz individually, when in CrossFire, I doubt they will be stable at all running both@1100MHz.

1050Mhz could be the sweet spot(again just talking numbers) regarding stability.

Basically, whatever's the first stable clocks, reduce them a touch for less hassle.

You wan't as much a hassle free time with dual cards as you can get, so you'll benefit in the long run.

Some games are worse than others when you are at the edge in (system overclocked) CrossFire/SLi, e.g BF3.

Your cpu must be close to the edge too, that definately won't help, if 4.7Ghz is rock solid then leave it there until you are more comfortable with the setup.

I'm not convinced your psu will be 100% stable either(don't run out and buy one on my guestimation though;)) as it's getting to the edge of requirements especially overclocked.

CTD is crash to desktop(driver has stopped responding...), but that doesn't rule out system cpu+gpu overclocking stability, the driver will be the first to crash in general even if it isn't the fault of the gpu's-they always get the blame but it's not always the gpu's.
 
Ah, ha. I have identified the problem!

Both clocks individually clock to at least 1200/1600 @ 1.2v.

The problem is that in crossfire the voltage adjustment is only being applied to card 1.

Anyone got any ideas?

Thanks
 
Cool, If your using Afterburner, tick these:

708c6734815cf43b7cd9bfd152ff6bda.jpg


Make sure your MSIAfterburner.cfg contains this:

[ATIADLHAL]
EnableUnofficialOverclocking = 1
UnofficialOverclockingEULA = I confirm that I am aware of unofficial overclocking limitations and fully understand that MSI will not provide me any support on it
UnofficialOverclockingMode = 1
AccessibilityCheckingPeriod = 0
UnifiedMemoryUsageMonitoring = 1

But, iirc, this didn't work for someone and he had to do something else that I can't remember, though it might just have been a single 7950, hopefully it'll work for you.

Remember and come back with an update.
:)
 
Thanks, I have done all this apart from the last 2 config changes. What do they do? I've give them a go tonight anyway.

Also I think I will reinstall latest versions of all drivers and overclocking program's tonight.

Do you think I should be disabling upls as well?

Thanks
 
Solved! Thanks guys.

ULPS seemed to be the culprit.

My only problem now is that unofficial afterburner overclocking doesn't seem to work.

I can however run at 1100/1575 @ 1.149v in crossfire - giving a Heaven score of 3700, which i am pretty pleased with.

Flashing the Windforce to the Sapphire bios may enable me to get to 1200/1600, but that is probably a job for another night.

Thanks again.

P.S any tips on getting unofficial overclocking working in crossfire wold be appreciated.

Cheers
 
RichH said:
Hi Guys,

I have 2 x 7950, 1 Windforce and Saphire OC.

On it's own the Windforce OCs brilliantly - 1200/1600 @ 1.2v. It might even go higher but I havn't unlocked it in MSI.

In crossfire however I can't even get to 1Ghz. 975Mhz seem to be the highest I can manage. The strange thing is I can get 975 on stock volts, but can't get any higher even with 1.25v.

Initially I thought the second card was just a poor clocker, but it doesn't make sense that i cant clock higher even with a significant voltage bump.

Am i doing something wrong?
Click to expand...

EDIT: NVM. There's two .dll files you have to download and put into your MSI folder for it to work, are your clocks stuck at 0 yeah? The thread on what to do is in GPU section somewhere, gives links to the files aswell.
 
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