• Competitor rules

    Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.

7950 Crossfire Usage issues..

How high can I safely take the voltage? I was running at 1.214 last night

Blimey you must have a stinker of a card to require such high voltage for 1000 core. I think what you need to do is find out, individually what both cards need to do either 1000/1400 or 1050/1500.

If not maybe we can ask that chap to create you a bios with lower clocks. Test the card individually and find out what voltage you need for each card.

Use Unigine Valley and see if you complete the benchmark safely. If you do then test a game for 20 minutes. You might well need an extra notch of voltage to be game stable.
 
No, the core is fine up to 1200, it's the memory that kicks off. Can't get past 1300.

Can you try over volting the memory? I've not had much luck over volting mine. Elpida memory really is crap. Nevertheless try bumping the mem voltage up to 1.625v or 1.65v and see if it helps.
 
I think your going about oc'ing the wrong way with dual cards, you should always find the limits of each card first in single mode and go with the lowest clocks-though they can run on different clocks but it's easier if they are matched.

You don't need to remove cards btw, just switch off CrossFire and change the display cable to the bottom card and thats the one that will render.

Your vram needs more juice too by the looks of it, try matt's suggestion on voltage and push the power slider up to 40 if needed.

:)
 
I think your going about oc'ing the wrong way with dual cards, you should always find the limits of each card first in single mode and go with the lowest clocks-though they can run on different clocks but it's easier if they are matched.

You don't need to remove cards btw, just switch off CrossFire and change the display cable to the bottom card and thats the one that will render.

Your vram needs more juice too by the looks of it, try matt's suggestion on voltage and push the power slider up to 40 if needed.

:)

+1.

Luckily both my cards match in being distinctly average. :D

Well, i say average. Technically the stock clock of the 7950 is 800mhz, with boost thats 925mhz. Both mine will do 1150 maximum so 225mhz core overclock isn't too shabby i suppose.

Memory stock at 1250mhz. I've been as far as 1563mhz on both cards without problems so far.
 
Does forcing constant voltage in AB not help alleviate the problem at all? I son't really understand why setting the clock and voltage manually doesn't stop all this.
 
Does forcing constant voltage in AB not help alleviate the problem at all? I son't really understand why setting the clock and voltage manually doesn't stop all this.

All that will do is stop your card from down volting at idle. Are you saying that your card is not stable no matter how much voltage you put through it?
 
I don't know mate - properly losing patience with it. Have put them on a popular online auction site. Will try again tonight but this is way more hassle than it should be. Guess this is why folk warned me off Crossfire!
 
I don't know mate - properly losing patience with it. Have put them on a popular online auction site. Will try again tonight but this is way more hassle than it should be. Guess this is why folk warned me off Crossfire!

Crossfire has nothing to do with a poor clocking gpu. What you need to do is find out which gpu is the poor clocker. It might take you some time to figure out but if you want the best results that is what you should do.

Why don't you read my overclocking guide so you can find the max for the core and the memory of each card individually. Then you will have a better idea of where you stand. Slow down and take your time.

http://forums.overclockers.co.uk/showthread.php?t=18431335
 
Oh I'm sure this is solvable if I'm willing to invest hours and hours and hours. But that's the thing isn't it? I've actually used your ocing guide before (it was really useful) and have got them running at a stable oc. It's just the core fluctuation that I can't seem to stop.

Think I'm going to simply get rid of the pair and invest in a single good GPU.

But like I said, I'll try a lot of the tweaks you've recommended tonight and see if I get anywhere.
 
If one or both of your cards are not stable at the clocks set then you will never get a smooth gpu usage.
 
As far as I can tell, yeah

If you set up msi on screen display correctly you can monitor gpu usage for both gpu's, core voltage to see if its boosting, temps etc. Enable it and play some games to monitor. Have you disabled ULPS as well? That's essential to do if you're overclocking on crossfire.
 
Yeah, did that a long time back. I think I might have confused you a bit - I was saying that i was getting a perfectly smooth OC prior to the bios flash. The only problem I had with the cards before any of this were the occasional boost spikes. Post bios updates it's now freezing and crashing. Apols.
 
Yeah, did that a long time back. I think I might have confused you a bit - I was saying that i was getting a perfectly smooth OC prior to the bios flash. The only problem I had with the cards before any of this were the occasional boost spikes. Post bios updates it's now freezing and crashing. Apols.

Go back to the old bios then and use the 50% power tune that will solve the boost spiking. :)

30% will be enough to get rid the spiking, even with a large overclock.
 
Back
Top Bottom