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So I decided to be a complete idiot and try to get this to work properly.

First I had an Asus HD6950 2GB which I have unlocked to 6970 specs.
Then what I did was buy an R6970 Lightning.

So now I want them to join together in perfect harmony. I have my ccc at the ready and MSI Afterburner as well. How should I do this?
This what what I currently see when I look at each card in Afterburner:

R6970 Lightning:



HD6950:

I don't get the question...put a crossfire bridge (or two, if you want), enable Crossfire in CCC, and enjoy your runt frames. What's weird about this?

Getting it to run well is the problem.
Right now it performs terribly with a huge amount of tearing. Which I am guessing is due to the fact that they are two different GPUs.

Welcome to Crossfire.

If you're seeing tearing but no other visual anomalies then you're just enjoying the amazing efforts of AMD's driver team as of late. You could try the beta frame pacing driver (which is supposed to be quite decent) if you're running a single 2560x1600 screen or smaller.

Waco wrote:

Welcome to Crossfire.

If you're seeing tearing but no other visual anomalies then you're just enjoying the amazing efforts of AMD's driver team as of late. You could try the beta frame pacing driver (which is supposed to be quite decent) if you're running a single 2560x1600 screen or smaller.

13.10 is the most recent beta driver isn't it? And this is for 1 1080p screen.

13.8 beta is the one with the frame pacing improvements I believe. http://techreport.com/review/25167/fram ... on-hd-7990

Waco wrote:

13.8 beta is the one with the frame pacing improvements I believe. http://techreport.com/review/25167/fram ... on-hd-7990

Afaik every beta since that one has had the frame pacing. I certainly have the option in my CCC.

So is it just vsync-related tearing then?

Yeah I get a lot of tearing regardless of settings

Try setting them to the same core and memory clock rates? Otherwise, try swapping the cards' positions. You might even be able to solve the loping problem by arranging your mismatched cards in the right order.

JustAnEngineer wrote:

Try setting them to the same core and memory clock rates? Otherwise, try swapping the cards' positions. You might even be able to solve the loping problem by arranging your mismatched cards in the right order.

The 6950 used to be my primary card but I made the 6970 my primary when I got that. Seemed like the right thing to do.
What exactly do you mean with "loping problem"?
As for matching their core and memory clock rates, I guess I should downclock the 6970 then. Not sure how much that will hurt the performance.

Enabling Vsync in the game or application always seemed to help with the tearing in my xfire rig. You gain a little latency which isn't great for twitch online shooters but for everything else its okay.

The "runt frame"/"micro-stutter" issue is that one of the GPUs in an SLI/Crossfire configuration typically takes longer to render a frame than the other one does.

One of the GPUs spits out a frame. You see that displayed until the second GPU has finished rendering the next frame. In the meantime, the first GPU is working on another frame. There's something about the Crossfire-X setup that causes one GPU to perform more slowly than the other, so you only see its output frame for a short while before it is replaced by a frame from the other one, which you see for a longer time because you're waiting around for the pokey GPU to finish its frame.

Since your GPUs are mismatched, if you put the faster card in the position where it would normally be lagging, it might actually partially make up the difference to smooth out the loping.

http://techreport.com/review/25167/fram ... n-hd-7990/

you could always just flash the 6950 with a 6970 bios it might help a little

i had a reference sapphire 6950 that i messed around with and i also did the "mod your bios to unlock the extra shaders" trick on it but i could also simply flash an equivalent 6970 bios on it also which also worked
remember most early moddable 6950's had a dual bios switch so even if you screw up flashing the 6970 bios on the 6950 you can always just flick the switch and boot into the secondary bios and flick it back while in windows and flash back to normal

if you are worried about the memory speed being too high on the 6950 you could just lower both slightly (iirc my 6950 did 1350mhz memory clock reliably but was a little odd at 1375mhz 6970 speeds) i dont think 25mhz will make much difference performance wise

you can also unlock extra clock headroom in afterburner by typing /xcl in the afterburner shortcut in the target box of the shortcut propertys (thats what i did with mine and i oc'd mine to 950mhz)
http://forums.guru3d.com/showthread.php?t=370201
you might have to make a custom fan profile in afterburner if you OC that 6950 (i did) to keep it under 60

you should be able to (with just a bit of tinkering) get them both at similar speeds (im guessing 940/1350 should be easily possible) which "MIGHT" help your screen tearing issue
if its a driver issue then you will have to go on a driver search to find one that works correctly

Proxicon wrote:

Enabling Vsync in the game or application always seemed to help with the tearing in my xfire rig. You gain a little latency which isn't great for twitch online shooters but for everything else its okay.

That's just it, I get tearing even with vsync enabled.

f0d wrote:

you could always just flash the 6950 with a 6970 bios it might help a little

i had a reference sapphire 6950 that i messed around with and i also did the "mod your bios to unlock the extra shaders" trick on it but i could also simply flash an equivalent 6970 bios on it also which also worked
remember most early moddable 6950's had a dual bios switch so even if you screw up flashing the 6970 bios on the 6950 you can always just flick the switch and boot into the secondary bios and flick it back while in windows and flash back to normal

if you are worried about the memory speed being too high on the 6950 you could just lower both slightly (iirc my 6950 did 1350mhz memory clock reliably but was a little odd at 1375mhz 6970 speeds) i dont think 25mhz will make much difference performance wise

you can also unlock extra clock headroom in afterburner by typing /xcl in the afterburner shortcut in the target box of the shortcut propertys (thats what i did with mine and i oc'd mine to 950mhz)
http://forums.guru3d.com/showthread.php?t=370201
you might have to make a custom fan profile in afterburner if you OC that 6950 (i did) to keep it under 60

you should be able to (with just a bit of tinkering) get them both at similar speeds (im guessing 940/1350 should be easily possible) which "MIGHT" help your screen tearing issue
if its a driver issue then you will have to go on a driver search to find one that works correctly

Thanks for the heads up but my 6950 is already using a 6970 BIOS. I tried overclocking the flashed 6950 before but didn't manage to get past 900Mhz. How high is your core voltage at those specs?

Guys - core clocks and memory clocks are matched in Crossfire mode (at least they were in the past...has that changed?).

I guess an easy test would be to clock the 6970 down to the level of the flashed 6950 and see if the tearing goes away. If it does, the clock matching isn't working properly and perhaps that causes issues with the new frame pacing stuff.

Ph.D wrote:

Proxicon wrote:

Enabling Vsync in the game or application always seemed to help with the tearing in my xfire rig. You gain a little latency which isn't great for twitch online shooters but for everything else its okay.

That's just it, I get tearing even with vsync enabled.

f0d wrote:

you could always just flash the 6950 with a 6970 bios it might help a little

i had a reference sapphire 6950 that i messed around with and i also did the "mod your bios to unlock the extra shaders" trick on it but i could also simply flash an equivalent 6970 bios on it also which also worked
remember most early moddable 6950's had a dual bios switch so even if you screw up flashing the 6970 bios on the 6950 you can always just flick the switch and boot into the secondary bios and flick it back while in windows and flash back to normal

if you are worried about the memory speed being too high on the 6950 you could just lower both slightly (iirc my 6950 did 1350mhz memory clock reliably but was a little odd at 1375mhz 6970 speeds) i dont think 25mhz will make much difference performance wise

you can also unlock extra clock headroom in afterburner by typing /xcl in the afterburner shortcut in the target box of the shortcut propertys (thats what i did with mine and i oc'd mine to 950mhz)
http://forums.guru3d.com/showthread.php?t=370201
you might have to make a custom fan profile in afterburner if you OC that 6950 (i did) to keep it under 60

you should be able to (with just a bit of tinkering) get them both at similar speeds (im guessing 940/1350 should be easily possible) which "MIGHT" help your screen tearing issue
if its a driver issue then you will have to go on a driver search to find one that works correctly

Thanks for the heads up but my 6950 is already using a 6970 BIOS. I tried overclocking the flashed 6950 before but didn't manage to get past 900Mhz. How high is your core voltage at those specs?

hmm are you sure you are using a 6970 bios? because the clocks that are on that screenshot are the clock speeds of a 6950
6970 "should" be 880mhz core 1375mhz memory
i originally thought you modded your own bios to just unlock the extra shaders so it had the 6970 shaders but not the clock speed
i had my 6950 @ 1.2v for 950 core and yeah it was around 900mhz at standard voltage

either way you should do what Waco says above me - just lower the clocks to match them up for a test, if the problems are solved when you do this (albeit at slightly lower performance) you know its the clocks if it doesnt fix it then it could be some other issue

I guess I screwed up somewhere and only unlocked the shaders (Or did I screw up when I put it in a different slot when adding the 6970?). I used to run the single 6950 at 900/1400 (with unofficial overclocking in Afterburner) but I couldn't really get it stable and it also got very loud. When I got the second card I reverted the first card back to default settings.

EDIT:
So I went back and tried to flash my 6950 to the 6970 BIOS. The basic winflash method gave me a "SubsystemIDs mismatch" error. So then I went and did it the command prompt way.
Normally at the end of it you should see some kind of message. I don't get any message. The card has not changed at all. It's a reference model too.
Come to think of it this is exactly what happened last time too, I ended up just unlocking the shaders with RBE and then trying to overclock the card to 6970 specs without any luck.

Ph.D wrote:

I guess I screwed up somewhere and only unlocked the shaders (Or did I screw up when I put it in a different slot when adding the 6970?). I used to run the single 6950 at 900/1400 (with unofficial overclocking in Afterburner) but I couldn't really get it stable and it also got very loud. When I got the second card I reverted the first card back to default settings.

EDIT:
So I went back and tried to flash my 6950 to the 6970 BIOS. The basic winflash method gave me a "SubsystemIDs mismatch" error. So then I went and did it the command prompt way.
Normally at the end of it you should see some kind of message. I don't get any message. The card has not changed at all. It's a reference model too.
Come to think of it this is exactly what happened last time too, I ended up just unlocking the shaders with RBE and then trying to overclock the card to 6970 specs without any luck.

before i go any further and explain how to do it (you can force it and it should still be ok) have you tried to underclock the actual 6970 yet to the same speeds as the 6950 just to see if that is what is causing you the issues?

before you do anything you should at least try and see if that fixes your issues

There is a check box in MSI afterburner setting to sync your clockspeeds on your cards. Just run them at the max core and memory speeds your unlocked card will run at. That should help with the mismatched speeds of the cards making them render the frames at the same speed. Also make sure you use the frame pacing driver.

f0d wrote:

before i go any further and explain how to do it (you can force it and it should still be ok) have you tried to underclock the actual 6970 yet to the same speeds as the 6950 just to see if that is what is causing you the issues?

before you do anything you should at least try and see if that fixes your issues

Yeah there is improvement. My current plan is to try and make the 6950 run at 6970 specs. Then I will only have to downclock the 6970 a bit to match them.
Sadly CCC and its PowerTune seems to be hindering my progress so I think I might have to do a registry edit to allow higher higher powertune and clocks in CCC as it was described Here. That or do the Afterburner edit f0d recommended.

vargis14 wrote:

There is a check box in MSI afterburner setting to sync your clockspeeds on your cards. Just run them at the max core and memory speeds your unlocked card will run at. That should help with the mismatched speeds of the cards making them render the frames at the same speed. Also make sure you use the frame pacing driver.

I've always wondered how exactly that function works. If it tries to match the secondary card to the primary card's clock (which it can't) or if it matches the highest to the lowest card or something else.


EDIT:
I just tried the method f0d linked

f0d wrote:

you can also unlock extra clock headroom in afterburner by typing /xcl in the afterburner shortcut in the target box of the shortcut propertys (thats what i did with mine and i oc'd mine to 950mhz)
http://forums.guru3d.com/showthread.php?t=370201

... and it doesn't work. Both the settings in Afterburner and CCC remain exactly the same for the 6950. (I did get the little popup saying the limits were increased and I should reboot.)
Does it only work on the primary card or something? I'm not even sure it did very much for my primary card to be honest. Any advice?

Compare this image to the picture in my original post:



The memory clock headroom seems a tad higher but that's about it, and it's for the card which doesn't need it anyway.

Major update. Big enough to warrant its own post in my opinion.

So as I mentioned in the previous post, I tried the MSI Afterburner -xcl method. That barely worked.
Then I tried RacerX. The executable version did not work but I did manage to make it work by manually editing the registry.

Lo and behold!

ASUS 6950:


MSI R6970:


ASUS 6950 in CCC:


Managed to increase my clock on the 6950 in both Afterburner and CCC and then I downclocked the 6970 to stock 6970 clocks in order to match it to the 6950. It's been an ordeal but it finally seems to work as intended.

Two things worry me though:
1) "Enable manual fan control" keeps automatically switching to Enabled in CCC. I worry it might be conflicting with Afterburner. And because the manual fan control in CCC is ass I really don't want it to.
2) I think this whole house of cards will come crumbling down as soon as I have to update the GPU drivers and/or Afterburner.

Any advice is always appreciated. And thanks for the help so far.