So many folks read the marketing label: "2 PCI-E 2.0 x16 interfaces with AMD CrossFire support" but not the actual board specification: " 2 way AMD CrossFire™ (running at x16, x4 bandwidth)"
Here's my experience with that: (playing DiRT3, my favorite @ the time...)
- Single 5770 : ~50FPS (in x8 slot)
- Dual 5770's : ~55FPS (second card in x4 slot on Intel ASUS LX motherboard)
- Dual 5770's : ~100FPS (AMD system x16 / x16)
- Dual 5770's : ~95FPS (Intel system x8 / x8 ASUS PRO motherboard)
Lots of things effect the amount of impact an x4 slot has:
- the game
- monitor resolution
- CPU power
- GPU power (the more you have the bigger the impact)
But, there's always some impact for x4. There's a small increase in price to get x8 / x8 to avoid the controversy altogether.
As always, your mileage may vary...............