AMD Crossfire - Cards running at low usage

[Stone04]

Hi, I have an ATI Radeon 6950 and have just bought a 6970 along with a crossfire bridge. After fitting the new card and the bridge, I've enable crossfire in CCC and downloaded and installed the application profiles, restarted my computer and fired up BF3.
After finding that I haven't had any kind of FPS boost, I downloaded AMD System Monitor, and ran it during BF3, but the graph shows that each card is only using about 45%-50% of its GPU? When I turn crossfire off and disable the second card, the graph shows that the one card is using about 80%-90% GPU. Can anyone please help me understand why this is? Shouldn't they both be pushing up to atleast 80% and giving me a much greater performance boost?

My other specs:

Windows 7 64-bit Ultimate
GA-990FXA-UD3
AMD Phenom II x4 840 @ ~3.2GHz
16GB DDR3 Ram - I think its at 1333MHz

Thanks!

 

[Rockdpm]

Nope the cards when in a dual GPU environment will share the load. kinda like two horses pulling a cart vs 1 pulling a cart.

 

[Rockdpm]

Also your system's Phenom 840 is a bottleneck..

 

[Stone04]

Oh, so your saying that the graphic cards are being held back by the CPU? Let's say I upgraded to a 6 core running at about the same speed, do you think that would be likely to increase the performance much?

 

[manofchalk]

Try overclocking the chip first, if performance increases a fair bit then you know its a CPU bottleneck.

If you do upgrade the CPU, advise an FX-6300 or better.

 

[Rockdpm]

Try overclocking the chip first, if performance increases a fair bit then you know its a CPU bottleneck.

If you do upgrade the CPU, advise an FX-6300 or better.

Agreed

 

[noob2222]

The 840 wont work, even at 5.0 ghz.

since you have the 990fxa motherboard, get the 6300 or 8320 and overclock them to 4.0ghz or higher.

I run the 8120@4.7 ghz with 2x 6970 1ghz GPUs and push 120 fps regularly, with a few drops in the mid 90s.

Cut off 2 cores (6100 version) it still hits 120, but dips to 60-70 fps.

4 cores is bad even at 4.7 ghz. cpu usage pegs at 100% and never drops, fps 90-50.

If your not into overclocking, the 8350 is stock clocked at 4.0 ghz, 6300 at 3.5 ghz and the 8320 at 3.5 ghz also.