2x Asus DirectCU II 6970 Crossfire woes

[Jay Dolan]

Hi,

I've been running a single DirectCU II 6970 for about 7 months and was overall quite pleased with its performance. I'm driving 3x 28" LCD's in portrait mode, for a native desktop res of 3600x1920 (3954x1920 with bezel comp). The single card performs adequately in most games.

Last weekend, I added a 2nd DirectCU II 6970 and got Crossfire setup on Catalyst 11.11. All driver settings are at their default values, with the exception (obviously) of "Enable CrossfireX."

The only title I'm really interested in running is Rise of Flight, a flight simulator which uses "alternate frame rendering" for SLI / Crossfire. Unfortunately, the game is running very strangely. It's the most pronounced "micro-stutter" I've ever seen -- it's more like surging. About 1 or 2 times a second, the game will run very smoothly for a brief moment, but then hiccup or "chug." I can hear the one or both of the cards' fans are surging and receding constantly.

Sure enough, when keeping GPU-Z's sensors running while I'm playing ROF, it looks like 1 GPU is running at full throttle (890MHz) while the other is basically idling along at 250MHz. I get the impression that ATI's power management stuff is just failing to recognize the load on the system.

Does this sound plausible? What can I do to force the cards to run at their full frequency all of the time? I use this PC for literally nothing else besides gaming, so I'm not very worried about power management.

Specs are as follows:

AMD Phenom II X6 1090T @ 4.0GHz (16x250)
Corsair H50 water cooler
ASUS Crosshair Formula IV, bios 2002
CPU-NB and HT link @ 2500MHz
4GB Corsair Dominator GT C8
2x ASUS 6970 DirectCU II 2GB
3x Hannspree 28" LCD 1920x1200
Corsair HX850 modular PSU
Coolermaster HAF 932 case
--
Windows 7 Home 64bit
AMD Catalyst 11.11

Attached are screenshots of CPU-Z and GPU-Z output. One thing that did catch my eye is that GPU-Z thinks my 2nd 6970 is only running on PCIE x8 rather than x16, but I've installed the card in the correct slot for 2x16 according to my motherboard manual. Apparently others have had this same issue.. but I'm not sure if it's legit, or just a GPU-Z bug.

Any ideas would be greatly appreciated!

Jay

[Jay Dolan]

Just an update.. Upon installing MSI Afterburner, I've confirmed:

1. When running any Source engine games, my 2nd GPU sits idle.
2. When running Quake based games, my 2nd GPU sits idle.
3. When running Rise of Flight, my 1st GPU runs at full speed but is only 60% utilized.
3a. My 2nd GPU flutters between 250, 500 and 890MHz (mostly 500MHz) and is 100% utilized the entire time.

Performance on the single card is totally adequate for Source engine and Quake games, but I'm still disappointed that the 2nd GPU isn't used at all. And my 2nd GPU's reluctance to step up to the plate on Rise of Flight is really frustrating. The surging, stuttering framerate leaves the game completely unplayable with Crossfire enabled.

Any help towards resolving this would be greatly appreciated!

Thanks,

Jay

[entropy13]

All I can say for now is that there must be something wrong with the drivers. Not "maybe installed incorrectly" wrong, but "these drivers from AMD are just so horrible" wrong. Maybe try older drivers first?

[DannibusX]

Did you install the latest Crossfire Profiles (CAP)? All I see in your post is that you installed the 11.11 Drivers.

[entropy13]

Originally Posted by DannibusX

Did you install the latest Crossfire Profiles (CAP)? All I see in your post is that you installed the 11.11 Drivers.

Then Rise of Flight shouldn't show usage at all on the 2nd GPU too if that was the case (latest CAPs not installed)?

[Jay Dolan]

Thanks for your replies guys!

I did have the latest CAP installed, yes. Last night, I tried flashing a new BIOS to the card from this website that, in theory, would keep my clocks above 800MHz at all times:

http://www.techpowerup.com/vgabios/9...48.110106.html

When I load this BIOS up in RBE, however, it shows that the clocks are the same as my default BIOS. I figured I'd give it a go anyway, so I made a bootable DOS USB drive with atiflash.exe and successfully flashed both cards with their BIOS switches in position 1. Rebooted into Windows just fine, but no change in the card's behavior at all.

So then I tried editing the BIOS myself in RBE, setting the clocks for all 4 modes to 890/1375 and default voltage. Flashed just fine, but I get a BSOD when trying to boot into Windows. What's up with that? Re-flashed back to my stock BIOS and I'm back at square one..

I also tried uninstalling all ATI/AMD drivers, and went as far as running DriverSweep in safe mode so that there were no traces of Catalyst on my system. A fresh reinstall of 11.11 last night put me right back to where I was.. GPU 1 at full speed but half utilized, GPU 2 at half speed and completely pegged. SO frustrating!

If this isn't a driver issue, the only other thing I can think of is that my power supply is insufficient, but I find that hard to believe. It's a very high-end PSU (Corsair HX850) with 70A on the 12V rails. I have a pretty sweet UPS / conditioner on the box, too, and it never shows a load over 420w, so I'm hardly straining the PSU if it's capable of what it says on the box.

What the f? Ya know?

[cadaveca]

Try the "EnableULPS" registry tweak. Search the registry for this key, change all listings with "1" to "0".

[Jay Dolan]

I tried that as well. There were 4 occurrences of that key, and I changed them all, then rebooted. No change at all -- does that sound right? I was a bit surprised at that one.

Oh, also, I tried running 3DMark 11 last night as well, and it behaved exactly like Rise of Flight: primary GPU just waiting on the second GPU, massive stutters and chop, 22 very erratic frames per second with Crossfire enabled versus a much smoother 32fps with it disabled

[cadaveca]

Something is not right, for sure. Sounds like, for some reason, the second card is not scaling the clocks up under load. the huge differences in clocks would be enough to cause the stutter.

We need to figure out why the clocks are not adjusting. Could be PSU, something in the OS, or even the card itself. Could be the board or some other oddity as well.

Do you have any third-party tools like MSI Afterbuner or something installed?

[Jay Dolan]

I do have Afterburner installed, yep. Great little tool! It's on-screen monitoring overlay is how I determined exactly what was going on.

I could go buy a 1200w PSU just to try it out, but that's $220 I'd rather not dump into this experiment. My current PSU should be adequate.

Tonight I'll try pulling the 1st card to see if the 2nd card functions correctly on its own and in the PCIe slot I have it in (slot 3). If it does, then I will have eliminated the card itself from the list of suspects. That'll leave PSU and Drivers in the lineup..

To test the PSU without buying a new one, I might also try underclocking both cards to, say, 700/1000. If they work correctly at that speed, then maybe the PSU is somehow just not enough :/

Btw, any ideas why I can't seem to create a working BIOS with RBE? Are there some golden rules around clocks and voltages that would prevent me from baking a BIOS that is just full-throttle all the time? Even if that's not the smartest idea long-term, it would be useful for determining if my system is capable of delivering enough power to these cards to run at full-speed. And why, when I load a BIOS from this website's database into RBE, do the clock speeds not align with what is advertised on the website? Something is very fishy with RBE for me..

[cadaveca]

Clock adjustment in BIOS edits is not recommended at this time. The driver will detect, override, or sometimes prevent booting when clocks are editted.

It could very well just be MSI Afterburner causing all the issues. You really need to have a "factory" installation of drivers and use default clocks on your GPUs when trying to pinpoint problems. MSI afterburner makes registry edits that may potentially cause problems with some configurations.

If you need real-time monitoring, you can always try GPU-Z. Unfortunately, it doesn't have an overlay like MSI afterburner or FPS reporting, but it will log things like clock speed, voltages, and temperatures while in the background. The difference with GPU-Z is that it is a MONITORING and REPORTING tool, rather than a tool that lets you adjust hardware settings.

MSI afterBurner will adjust clock domains for the GPU while under load, and as such, may have input settings that are preventing the "slave" card from clocking properly.

[Jay Dolan]

I had all of these symptoms before installing Afterburner. GPU-Z was giving me a decent idea of what was going on, but I installed Afterburner to get a clearer picture and confirm -- which worked. I've not actually enabled any of the clock or fan overrides available in Afterburner; I'm using it purely for monitoring at this point. Thanks tho!

Btw, if not for editing clock speeds, then editing the BIOS of the 6970 is pretty pointless right?

Jay

[cadaveca]

Yeah, I mean, AMD seems to have things locked down pretty tight. You can adjust some things just using CCC, once CCC is customized to open up a bit more, but I haven't had alot of fun with BIOS edits on 69xx-series cards.

At the same time, your CPU isn't really enough to push those cards fully. Of course, this only usually appears as card not getting full utilization, not the clocks failing to scale(which kinda eliminates that problem). If your CPU is overclocked, it is fully possible it's a fault of the PSU, if you've covered all the basics. CPU and each video card are fully capable of pulling more than your 850w PSU can provide while running Eyefinity. Figure 300W for each, and you're already on too little power.

If you want to force 3D clocks for all loads, try the RacerX mod. It will allow you to set 2D and 3D clocks, as well as the minimums and maximums in CCC overdrive. BIOS edits are not needed.

[Jay Dolan]

My CPU is indeed overclocked (4.0GHz, 250x16) and water-cooled (Corsair H-50). I will try knocking it back down to stock clocks and see if that makes a difference. I know that, in most games, I'm CPU-bound, but that is definitely not the case in Rise of Flight, and certainly not when running at 3958x1920 with 8x FSAA

I'll look around for that RacerX mod as well; it sounds really promising.

Thank you guys for your help! I'll post back with some updates tonight.

Jay

[Mike0409]

Jay,

I had similar issues when I was running 2, 6950's unlocked to 6970's. An MSI and a Sapphire, and I have a similar build that you have.

I chalked it up to Drivers/Crossfire Profiles not being correct, as well as the game not having full support for Crossfire. Source games and various other games would work, but when I would play Rift or WoW I got better performance from an GTX 480 than 2 crossfired cards.

I also experienced issue's with 3D Mark 2011 and much worse performance. I blamed this to be on the driver immaturity more than anything, and this was tested last November..so I am not sure how much that has been addressed since then.

This battle went on for quite a while until I decided to throw in the towel and go with a single GPU solution. Hope this isn't the case with you, if I can help let me know..I spent long nights trying to figure those friggin cards out only to be left with nothing but defeat in the end.

[Jay Dolan]

That blows Mike

Hopefully I'll find out a little more tonight. Who knows, might even find an answer.

Cheers,

Jay

[Darkleoco]

Just to throw it out their when I was doing the ULPS registry change I had quite a few more than just 4, idk if that could be your problem but ensuring all of them are changed again could not hurt.

Also I doubt you would need a new power supply but if you were to get one it could be a decent investment depending on how old your current PSU is.

[Jay Dolan]

I searched the registry for the key and hit F3, modifying them all until it looped back around, and then I looped through again just to be sure

The PSU is only 8 months old. I bought it at the same time I bought my first 6970 (April this year).

Thanks Darkleoco!

[yogurt_21]

just a thought but have you tried swapping the crossfire bridge for another one? If the bridge is bad it would explain your issues.

[Jay Dolan]

Ah, that's interesting, no I haven't tried that. I've got a bunch of things to test out now..

I was actually working until 11pm last night (yay, 14 hour day) and didn't have a chance to try any of the ideas mentioned above. I'll get on that tonight, tho, and will report back.

[Jay Dolan]

Fixed!

Turns out my new card had a bogus HSF application. Enabling the temperature readout in Afterburner revealed that the GPU which was throttling down was doing so because it was hovering around 100'C! I popped the HSF off, cleaned out the old, dried up thermal compound, applied some CoolerMaster grease, slapped it back together, and tada! Everything works!

Well, almost.. apparently V-sync does not work with CrossFire :|

I sincerely thank all of you guys for your replies and advice! I'm thoroughly enjoying running Rise of Flight at max quality settings across 3 screens

[Darkleoco]

Originally Posted by Jay Dolan

Fixed!

Turns out my new card had a bogus HSF application. Enabling the temperature readout in Afterburner revealed that the GPU which was throttling down was doing so because it was hovering around 100'C! I popped the HSF off, cleaned out the old, dried up thermal compound, applied some CoolerMaster grease, slapped it back together, and tada! Everything works!

Well, almost.. apparently V-sync does not work with CrossFire :|

I sincerely thank all of you guys for your replies and advice! I'm thoroughly enjoying running Rise of Flight at max quality settings across 3 screens

V-sync should work with CrossFire just fine

Good to hear your second card is working though

[Jay Dolan]

There are dozens of threads around the 'net of other Eyefinity + Crossfire users who can not get v-sync @ 60Hz to work. I guess the drivers are trying to sync at 120Hz instead (for dual-GPU setups).

[Darkleoco]

Originally Posted by Jay Dolan

There are dozens of threads around the 'net of other Eyefinity + Crossfire users who can not get v-sync @ 60Hz to work. I guess the drivers are trying to sync at 120Hz instead (for dual-GPU setups).

Interesting to know since I am always looking to upgrade to eyefinity. Seems like it could be annoying if their isn't any fix people have cooked up :/

[Jay Dolan]

Unless there's a legitimate reason why it can't be done (hardware limitation), I'd have to imagine that they'll fix it soon

In the meantime:



Yup, that rocks.