BF3 - Single Radeon 6850 runs better than 2x 6850 in Crossfire

[TC10284]

All,

I am having performance issues in BF3. I have 2x Gigabyte HD 6850 GVR685OC-1GD Radeon 6850 video cards in Crossfire mode. I will post the rest of my system specs below.

Basically, Battlefield 3 runs better with Crossfire disabled. It is smooth as silk when running at 1920x1080 on a single 6850. But as soon as I enable Crossfire mode, my FPS drops pretty low when looking over the battlefield (long distance) or when I get into a lot of action with smoke/fire.

I have tried numerous things. Even wiping and reformatting my system. I first tried using the latest drivers for my motherboard (Gigabyte GA-MA790XT-UD4P) from their website. Same performance issues with Crossfire.
I've tried getting the latest individual drivers for each piece of hardware in my system (chipset, graphics, audio, NIC) - even tried AMD Catalyst 12.6 Beta.
Same performance issues with Crossfire.

I've tried AMD 12.6 CAP profiles for BF3.
Same performance issues with Crossfire.

A single 6850 runs much smoother than 2x in crossfire, which I would definitely not expect. I wouldn't think it would be my CPU since the game runs great with Crossfire disabled, unless the CPU isn't enough to push 2x 6850's? I am very tempted to just rip the second 6850 out...

The CPU temps hit up to the low 50's. The GPU temps hit low to mid 50's. The CPU idles around 37*C. The GPUs idle around 40*C.

> Mainboard : Gigabyte GA-MA790XT-UD4P

> Chipset : AMD 790X

> Processor : AMD Phenom II X4 945e @ 3000MHz

> Physical Memory : 8192MB (4 x 2048 DDR3-SDRAM )

> Video Card : AMD Radeon HD 6800 Series (two 6850's)

> Hard Disk : Western Digital WD10 EALX-009BA0 SATA Disk Device (1000GB)

> DVD-Rom Drive : ELBY CLONEDRIVE

> DVD-Rom Drive : HL-DT-ST DVD-RAM GH22NS30

> Monitor Type : Toshiba TOSHIBA-TV - 40 inches

> Monitor Type : Asus ASUS VH242H - 23 inches

> Network Card : Intel 82574L Gigabit Network Connection

> Network Card : Realtek Semiconductor RTL8168/8111 PCIe Gigabit Ethernet Adapter

> Operating System : Windows 7 Professional Professional Media Center 6.01.7601 Service Pack 1 (64-bit)

> DirectX : Version 11.00

Power Supply - Corsair 650w

GPU-Z:
http://gpuz.techpowerup.com/12/06/20/g2s.png (first screenshot I took)
http://gpuz.techpowerup.com/12/06/20/dmf.png (second screenshot I took after closing/reopening GPU-Z)
http://gpuz.techpowerup.com/12/06/20/7kr.png

What is going on?

 

[borisvodofsky]

It's most likely your CPU. It's not fast enough to feed the crossfire.

BF3 is a very cpu intensive game, especially multiplayer.

You're going to need to overclock it to 4.0ghz

Also make sure your memory frequency and timings are set correctly in bios

Consider investing in 2 sticks of 4gb 1600mhz memory, it's 15-20% performance boost in GAMES compared to 1333.

4 sticks of memory is bad, except on x79

 

[fralexandr]

i was under the impression that there was almost no benefit moving from 1333 to 1600 unless you were running llano or some form of integrated...

http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3/6

 

[borisvodofsky]

i was under the impression that there was almost no benefit moving from 1333 to 1600 unless you were running llano or some form of integrated...

http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3/6

1600 makes a big difference vs 1333, THIS you can feel.

2133 however makes almost no difference except bandwidth and latency. (not the i can feel it kind.)

 

[gorcorps]

1600 makes a big difference vs 1333, THIS you can feel.

2133 however makes almost no difference except bandwidth and latency. (not the i can feel it kind.)

Almost everybody that posts in the hardware forums here says different. Every recommendation I've seen includes going with 1333 if it's cheaper because nobody has ever seen a noticeable difference between that and 1600.

 

[TC10284]

So is there anything I can do?

 

[gorcorps]

So is there anything I can do?

OC your CPU and see if it helps at all. If so then you know where to point the finger.

 

[Dankk]

Also, you might get more help if you post this in the Video Cards & Graphics Forum. You'll find far more techies and graphics enthusiasts there then you'll find here. In PC Gaming we usually just talk about the games.

 

[raasco]

I have a Sapphire/ASUS crossfire setup with my 2500K. There is a huge improvement in crossfire vs single gpu setup. Are you using the BF3 crossfire profile?

 

[TC10284]

I have a Sapphire/ASUS crossfire setup with my 2500K. There is a huge improvement in crossfire vs single gpu setup. Are you using the BF3 crossfire profile?

Yes, I was using the BF3 crossfire profile.