6870 cf + BF3 Ultra Problems

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r0b0ts

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I thought I'd post this here to see if anyone else is experiencing the same issues I am with Battlefield 3 and my crossfire 6870's in Ultra.

The Problem:

Put simply, everything works fine as long as I keep my settings at ultra but with textures and shadows on high and no msaa. If I increase any of those three settings to Ultra (or 2x msaa) the game will drop frames from 60+ fps to 15fps or even completely pause, leaving the screen frozen for 1 to 5 seconds and even the sound will fade, and come back when the framerate returns.

If I play like this for too long eventually the game will crash out.


Attempts at solving:

I don't have any issues with any other game. I've tried every recent driver revision and CAP. Most run worse creating the same problems even at lower settings. The 11.11 vanilla and the 12.1 preview seem to run best. CAPs only create more of a problem in any combination.

I've taken care to uninstall and scrub the system between driver installs each time. I've cleaned out the registry.

The cards are not overclocked. The i7 920 cpu is overclocked, but I've tested it with and without overclocking and with and without hyperthreading. No difference.

I've disabled the onboard realtech sound (I play through a USB logitech headset anyway).

It's not a huge deal as the frame rate is great with the settings I've figured out, but I didn't pay for two graphics cards to NOT run the game at the highest settings. I've considered parting the cards out and selling them to buy nvidia cards to see if they will do what I need. Maybe I'm just an idiot and overlooked something?


Any and all advice is welcome. Thanks.

System:
i7 920
x58 asrock mobo
6gb trichannel ram
BF3 installed to kingston ssd
1920 x 1080 resolution (2nd monitor attached but not used in game)
logitech surround sound usb headphones
850w power supply

All temps and wattages are in normal ranges.


-r0b0ts
 
The problem you are experiencing is FrostBite 2's lack of support for dual-GPU systems. I'm sure that if you went back to a single card, your frame-rates would improve. But from what I have seen on the Battlelog and Battlefield3forums.com forums, there are lot of complaints coming from AMD graphics card owners regarding CrossFire issues.
 
It could also be a vram limit as well. BF3 apparently uses more than 1gb of vram in Ultra settings. The same thing happens to me with my 2x6870s. I just decided to run everything in high and i run into no issues anymore.

Perhaps crossfire (or the drivers?) doesn't do well with vram limits? Single card seems handle it fine without all the pauses and glitches, but then of course the framerate is significantly lower.
 
Majinhoju said:
It could also be a vram limit as well. BF3 apparently uses more than 1gb of vram in Ultra settings. The same thing happens to me with my 2x6870s. I just decided to run everything in high and i run into no issues anymore.

Perhaps crossfire (or the drivers?) doesn't do well with vram limits? Single card seems handle it fine without all the pauses and glitches, but then of course the framerate is significantly lower.
Click to expand...

Exactly right. Keep in mind that even though you have a total of 2GB or VRAM between the cards, each GPU can only access 1GB. I can only run Ultra settings with cards with 1.5GB or RAM or more. My 1GB cards run High with 2XMSAA with no issues.
 
Majinhoju, you might be right. I feel like I saw benchmarks somewhere of similar crossfire setups running on ultra, thought. The bottleneck was adding 4x msaa but not the other settings.

I didn't realize when I bought the cards that games don't use the vram from both cards. Is that correct?
 
Crossfire uses alternate frame rendering, which means the GPU's take turns rendering each frame. Each GPU can only access the available RAM on it's respective card. BF3 will easily chew up 1GB or RAM with Ultra settings, and when it runs out, your card will studder and even crash.
 
Gotcha.

So here's a question. On a number of sites there are benchmarks for a variety of graphics cards running a variety of settings, including 1gb single cards running in Ultra.

Here's pc perspective's review: http://pcper.com/reviews/Graphics-C...esting-and-Image-Quality-Evaluation-Day-1/Out

Sure, the framerate is lower due to taxing the cards, but they seem to run fine without crazy hitching and stuttering.

Is my issue then a combination of CF plus the limited vram? I can test when I get home later to see if it'll run Ultra with just one card without the problems. Of course, I'd rather have the higher frames than the slightly better visuals, but this still seems odd.
 
You are running out of vram. This has nothing to do with running multiple cards. This is a text book definition of hitting the vram wall (sudden, drastic drop in fps - lowering MSAA or other vram intensive settings results in a massive gain). Use Afterburner to plot your vram usage in it's OSD. Note that Afterburner will display double your actual vram usage when CF is enabled. I hit 1.5-7GB of vram usage @ Ultra settings @ 1920x1080.

The article you linked is over the Beta's performance. The beta did not have Ultra textures (more vram usage), and was missing several other Ultra graphics options.

I would recommend using FXAA instead of MSAA to conserve vram - this may let you increase your texture quality and should be a good compromise. Short of buying 1.5GB+ cards it's really your only option - software isn't going to fix this.
 
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confirming what others are telling you, your running out of VRAM

i have 2x 1Gb 560 Ti's in SLI and experience more or less the same thing you do if i push settings too high and run out of VRAM
 
I think crossfire is still playing a role somewhere in the mix. I don't know exactly why, but here are my experiences in Ultra settings: (this happened to me in the beta btw)

Dual Card: Great framerate for the first 60 or so seconds, then stutter, then pauses in gameplay while it loads more of the level.

Single card: average/decent framerate but minus gameplay pauses.

Once I drop the settings down a bit so i don't hit the vram cap, crossfire runs like a dream throughout the entire map.

I'm thinking something with crossfire, either the technology itself or something driver related just doesn't like hitting those vram caps.
 
r0b0ts said:
Gotcha.

So here's a question. On a number of sites there are benchmarks for a variety of graphics cards running a variety of settings, including 1gb single cards running in Ultra.

Here's pc perspective's review: http://pcper.com/reviews/Graphics-C...esting-and-Image-Quality-Evaluation-Day-1/Out

Sure, the framerate is lower due to taxing the cards, but they seem to run fine without crazy hitching and stuttering.

Is my issue then a combination of CF plus the limited vram? I can test when I get home later to see if it'll run Ultra with just one card without the problems. Of course, I'd rather have the higher frames than the slightly better visuals, but this still seems odd.
Click to expand...

Because they are not telling you the whole story. The game is a console port. Hit detection is awful!!! Client side hit detection. The review sites will never tell you what the game is really like. They would never get another product to review.
 
I'm with you, Majin. Seems to be something funny when both cards are going instead of one.

Currently I can run everything at Ultra exept for textures high, shadows high, no msaa, full fxaa, hbao (I hope those are the right letters), 1920x1080 (or 1920x1200 on my other monitor). Push anything else up and it hits the wall.

I'm wondering if I want transparent 2x msaa what else I'd need to drop to make that work...
 
Turning off AO would be a start... I honestly think your best bet as far as overall image quality is concerned is to ditch MSAA in favor of FXAA with higher texture/shadow quality if possible. 2x MSAA is barely noticeable when high FXAA is enabled.

from:
http://www.hardocp.com/article/2011/11/22/battlefield_3_multiplayer_performance_iq_review/5

"FXAA High provides an image nearly identical to 4X MSAA without the performance loss."

Read: http://www.hardocp.com/article/2011/11/02/battlefield_3_single_player_performance_iq_review/6
 
I have a pair of 6870's also, and performance was mostly ok until recently when I downloaded the 4gb patch/expansion. All the new levels were giving me huge performance problems, it would bog down regularly and I would just be getting 20 frames or so. I was using high settings with 4x AA no FXAA. Even with one card it would bog down to 15 frames or so.

I'm not sure what the deal is, but I went down to 2x AA and everything plays fine now, so it sounds very similar to your experience. I personally don't really like FXAA because of how much it blurs, but it looks like the best option now for this game and my hardware.
 
I read those posts too, -Sn1PeR-. That's why I go with fxaa only, but I do like the benefit of aa on transparent textures, so I'm wondering about playing with the options to get that to work.

As for the difference between high and ultra textures or high and ultra shadows I'm not sure that I notice a huge difference. It's subtle and nice for screenshots, but when I'm running and gunning it doesn't affect me as much as the jaggies along a fence or in the edges of swaying branches.
 
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