HD 5770 crossfire LAG in HD1080p videos

TKCPrime

Distinguished
May 9, 2011
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18,510
Hey there guys. I'm new here but this site helped me a lot in the past. I'm curious about a problem I have. My specs are as follows:

CPU: QuadCore AMD Phenom II X4 Black Edition 955, 3200 MHz (16 x 200)
Motherboard: Asus M4A87TD Evo (3 PCI, 1 PCI-E x1, 2 PCI-E x16, 4 DDR3 DIMM, Audio, Gigabit LAN, IEEE-1394)
RAM: 2x4 GB 1333 MHz
Video Card: 2x Sapphire HD 5770 1GB Xfire (16x/4x)

My problem is with Transformers 2 1080p IMAX version. Everything seems to be fine up until the forest battle, when the screen switches to IMAX profile. It slows down so much it's unwatchable. I've tried different codecs but none seems to be working, I've tried different players no good. I have a 40" LCD TV hooked up to my Video cards via HDMI.
Black Hawk Down 1080p plays just fine, so I don't know what is the issue here.