Microstuttering experiment with 7950 Crossfire, use two bridges instead of one.

[antony209494]

Sometime those mobo manuals are quite wrong and it looks like this was one of those times. If the cards needed it, then there's no way AMD wouldn't mention it.

They definitely don't need two to work. Question is if two result in better performance (in most cases the answer is no). Anyway let's wait for the crossfire fix at the end of the month and see if that actually fixes anything.

 

[cadaveca]

1 bridge = Insane flicker-fest

2 bridges = Happy gamingz!

Flicker usually indicates a bad bridge(as per AMD, FutureMark and XFX support).

Could have been one of your card's Crossfire fingers was funky.

 

[erocker]

They definitely don't need two to work. Question is if two result in better performance (in most cases the answer is no). Anyway let's wait for the crossfire fix at the end of the month and see if that actually fixes anything.

You should check out FRAFS and FRAPS as I linked to in a earlier post. Try one bridge, then two and see if there are any differences in frames. I can test it out in a bit.. I got a whole bunch of new tech at work I'm figuring out currently.

Could have been one of your card's Crossfire fingers was funky.

That was my thought too at the time, however I have plenty of CrossFire bridges to test and it didn't matter. It was most likely one of the connectors on a card that was funky... But it needed two.

It was two of these cards btw: SAPPHIRE Toxic 100269TXSR Radeon HD 4890 1GB 256-b...

 

[antony209494]

Sometime those mobo manuals are quite wrong and it looks like this was one of those times. If the cards needed it, then there's no way AMD wouldn't mention it.

Flicker usually indicates a bad bridge(via AMD, FutureMark and XFX support).

Could have been one of your card's Crossfire fingers was funky.

Agreed! Could be a bad bridge. Dave are you still on Catalyst 12.10? If yes then why? What problems do you have with the new drivers?

 

[cadaveca]

Dave are you still on Catalyst 12.10? If yes then why? What problems do you have with the new drivers?

My system specs are nearly never accurate. I am using the 13.6 Beta 2 right now on P9X79 Deluxe with just one VGA. I'll get rid of them right now.

That was my thought too at the time, however I have plenty of CrossFire bridges to test and it didn't matter.

Doesn't matter anyway, but in general, with strange flicker, first thing to check is bridges and fingers.

 

[qubit]

AMD's driver itself (CURRENTLY) will tell you to connect BOTH bridges when none are connected. But you aren't an AMD GPU user, so I'm not sure why you are even offering info, because you'd have no idea that that was the case.

That's why I made the first comment I did in this thread. The driver tells you to connect both. Why? I dunno.

I've actually been waiting for someone to bring up this topic, since I saw this many times in the past 6-8 months.

1 bridge = Insane flicker-fest

2 bridges = Happy gamingz!

Well there you go, that's consistent with what I said that AMD would tell you if they're needed. Therefore I'm not surprised that connecting just one would lead to erratic results.

 

[cadaveca]

Well there you go, that's consistent with what I said that AMD would tell you if they're needed.

Not really.

 

[qubit]

Not really.

Yes really. You just seem to like negating everything I say.

erocker's experience and the instructions in the driver prove it.

EDIT: I mean they prove what I'm saying.

 

[antony209494]

Yes really. You just seem to like negating everything I say.

erocker's experience and the instructions in the driver prove it.

Oh please don't start arguing for such a stupid thing now...

 

[qubit]

Oh please don't start arguing for such a stupid thing now...

Check the previous comments, it's not me starting it.

 

[OneCool]

That's from a bit overt 2 years ago, and drivers have changed so much that this is a question worth asking again. The whole "ask google" things is getting really old, BTW. Sometimes people would like a conversation about a subject to answer questions, or just sort things out in their head. The only dumb questions are those not asked.


However, personally, I see ZERO difference. I could grab a second card off my shelf and check it again, but I don't have matched pairs now, just 7970 and 7950. Waiting for my second 7970 to be returned from being out on loan.

Can I borrow your 7950 when your 7970 gets back :shadedshu





I remember when cf and sli was first released they said it would all be incorporated into the motherboard eventually .... not sure how long EVENTUALLY is tho

 

[cadaveca]

Can I borrow your 7950 when your 7970 gets back :shadedshu





I remember when cf and sli was first released they said it would all be incorporated into the motherboard eventually .... not sure how long EVENTUALLY is tho

Early SLI had PCBs to swap around, or pin jumpers to move.

Early Crossfire had an external cable to connect both cards.


I've run multi-GPU since it came out, from both sides, and it HAS gotten better, and less complex for the end user. Those external cables for crossfire were a huge pain in the butt, and I had to replace more than one of them, for $50 each.

SLI was much simpler, the ASUS boards I used has PCBs to flip, while DFI had jumpers on the board. That still included having to connect a bridge between the cards.

Today, with both, we just connect the bridge. I understand that both CrossFire and SLI now use PCIe as well as the bridges, although I am pretty sure that SLI ALWAYS requires a bridge, but Crossfire can be done without it on lower-grade cards. I've always wondered why they couldn't offer the same with the high-end cards too, but having that cable linking the cards, just makes a physical impression that I don't really want to go away.

 

[OneCool]

Early SLI had PCBs to swap around, or pin jumpers to move.

Early Crossfire had an external cable to connect both cards.


I've run multi-GPU since it came out, from both sides, and it HAS gotten better, and less complex for the end user. Those external cables for crossfire were a huge pain in the butt, and I had to replace more than one of them, for $50 each.

SLI was much simpler, the ASUS boards I used has PCBs to flip, while DFI had jumpers on the board. That still included having to connect a bridge between the cards.

Today, with both, we just connect the bridge. I understand that both CrossFire and SLI now use PCIe as well as the bridges, although I am pretty sure that SLI ALWAYS requires a bridge, but Crossfire can be done without it on lower-grade cards. I've always wondered why they couldn't offer the same with the high-end cards too, but having that cable linking the cards, just makes a physical impression that I don't really want to go away.

Yep.Had the old Sapphire 1900XT CF edtion.(the 2900xt cf too) in conjuction with the 1900xtx.
When it worked it worked good but would go ALL TO HELL sometimes

 

[Ephremius]

I feel special, I actually got people to test an idea... SHELDON AND FELLOW BIG BANG THEORY FELLAS, HERE I COME!!!! YEHU ~

 

[INSTG8R]

Yep.Had the old Sapphire 1900XT CF edtion.(the 2900xt cf too) in conjuction with the 1900xtx.
When it worked it worked good but would go ALL TO HELL sometimes

I did the X1900XT Crossfire thing too. After that I have just always bought the Flagship ATI/AMD card ever since...

 

[erocker]

GRID 2 single GPU:

GRID 2 CrossFire:

Cards running at 1100/1500 for both tests. The graph definitely shows something however with this game in particular you cannot notice any kind of stutter, runts, skipped frames whatsoever.

 

[cadaveca]

GRID 2 single GPU:

http://img.techpowerup.org/130627/grid2single.png


GRID 2 CrossFire:

http://img.techpowerup.org/130627/grid2_xfireTime.png


Cards running at 1100/1500 for both tests. The graph definitely shows something however with this game in particular you cannot notice any kind of stutter, runts, skipped frames whatsoever.

Gives a good idea of the effect of adding the second card aggravating the problem.

At the same time, it has been mentioned that FRAPS (no matter what part of it you use) doesn't show the full story, and that you need to capture the data over the DVI or whatever cable, not from within the same system. Perhaps the output over the cable is smooth, but this software has it's own impact on performance metrics and shows issues that aren't present over the DVI cable. AMD could have already implemented some sort of fix for many games..they do seem to have indicated that they have been working on per-game fixes for some time.