had some trouble with the new COD4 1.7 patch. I was told to reinstall video drivers. I did. I installed ATI CCC 8.6.

Now my fps is half what it was. 3dmark06 was 16800, now 11500.

Ok when i got home i tested each card individually on 3dmark06 and crossfire. individual cards score higher than crossfire. Here are the results.

card 1, pcie slot 1 (second card removed)
overall score: 11741
sm2.0: 4720
sm3.0: 5315
cpu: 3446

card 2, pci slot 2 (other card removed)
overall score: 11741
sm2.0: 4720
sm3.0: 5315
cpu: 3446

both cards with crossfire enabled, pcie slot 1 primary
overall score: 11548
sm2.0: 4619
sm3.0: 5192
cpu: 3446

Both cards plugged in with 6 pin PCIe plug and the crossfire bridge installed.

GPUz says crossfire enabled and both cards are at 16x.

CPUz says (in the mainboard tab) graphics interface, 16x

ATI CCC says crossfire enabled.

I have noticed when two cards are installed, only the primary card's fan ramps up with usage. The other card's fan stays at one speed.

all of the parts in my sig are less than 60 days old. I have had no events of power surges, over heats, etc.

My 800w psu is also new and has 4-12v rails with a combined 56A.

I read in this forum http://www.visiontek.com/forum/vie [...] ebf12a07c5 that this guy was told by ATI that the X38 boards are not communicating properly between PCIe slots.

7 days ago everything worked fine with CCC 8.5 and COD4 1.6 patch.

Try reverting back to 8.5

Just a thought...have you tried the hotfix for 4870...i found that xfire scaling was much improved in certain games....but then i never had such problem like yourself.

I doubt it would be the hardware .....more likely messed up drivers. Worst comes to the worst ...try a new windows install....or do a test with a new install on new partition first.

At first i thought drivers. After 3-4 days i got tired of chasing drivers. So, yesterday i reformatted and reinstalled WinXP. I installed CCC 8.5. Same problem.

My dumbarse, reinstalled COD4 patch 1.7 before i tested crossfire with 3dmark06. I thought afterwards that it could be the COD4 patch 1.7. I uninstalled COD4, but i still have the problem.

Could it be the patch? This all this started after COD4 1.7. I guess another install of WinXP tonight and leave off COD4 until i test it.

No, i have not tried the 4870 hotfix. Would it still work for the 3870? That has been suggested by others.

bump