I have an AMD A8-3870 OC@3600 MHz on a Gigabyte GA-A75-D3H with 8GB Ram 750Watt PS 80Plus
my Problem is the Graphic cards... i have two HD 5830 connected via Crossfire and am using the latest driver from AMD "Catalyst 12.6"
3D Mark Vantage or 11 the Crossfire is working good even in Heaven there is a significant improvement about 80% more
but when you come to games, all of them, the system works with a single card (Crossfire disabled) better than with two.
i tested it with Max Payne 3 (latest update for Crossfire), Need for Speed run, Fifa 2012, Prototype 2
all of them are dropping down about 10 frames/s or more (tested via Fraps)
where can the problem lay on?
maybe the problem is with the connection between the cards i am more familiar with sli setup but i would guess that crossfire is pretty similiar, so i would say replace the connector between the two cards and if that does not fix the problem then i would contact AMD and get the cards sent in for techinical support or return the cards and get new ones. hope i can help
i could be wrong about this but i am pretty sure that 3D Mark Vantage is more gpu usage and less cpu then games use, maybe it is something with your cpu bottlenecking, i doubt thats the problem but i am just trying to help, i hope i can, if i am wrong sorry.
You biggest issue is that your motherboard wasn't designed to support crossfire. One PCIe lane is running at x16 and your other slot is only running at x4 speed. What that means is that because any time you crossfire your system automatically syncs both cards to run at which ever card is the slowest... so both cards are most likely running at x4 speed.
In order to get good results when using crossfire you need both cards either running at x16x16 or x8x8 speed.
i thought that one of the cards might be defect, so i tested them separately and both worked just fine. no heating problems lower card Max. Temp. 50C upper card max. 65C (in heavy duty)
the Crossfire problem is only with games, by Benchmark programs such as Vantage the score goes from P13884 to P17549 and Heaven score rises from 804 to 1576 points.
on the other side Max Payne 3 works single card 50-60 frames and in cross fire about 40-45 frames, Prototype 2 from 40 frames single, drops till 30 frames Crossfire.
Rage33 you are right i checked with GPU-Z the second PCI-E is working 4X, i checked some tested to see the difference in performance, and it is about 2-3% less when both works at 8X, so i will be glad if if i lose only that percent in games.
i thought it might be driver problems (which i think it is) but i got the last cap from AMD that solves such problems, i even downloaded the (Catalyst 12.7) but still the same