Idiot here, whats the different of a bad motherboard and a good one?
More fps? xD

FPS wise - perhaps 3% at most.

A good motherboard might give you SLi or Crossfire, newer CPU support, better RAM support, more overclocking, RAID etc.

ok, thanks

Three percent? I heard that was only because the motherboard would secretly increase FSB just a little.

Generally, the better boards give you more overclocking options, are more stable when they're used to overclock, and allow more hardware configurations (like newer CPUs, more than one graphics card, etc). The better chipsets will also give you a slight performance boost, but I doubt you'd notice unless you measured it.

If you're not planning on overclocking, and aren't going to be running any kind of exotic setups like triple SLI then you don't need an expensive motherboard.

Quote from hrtburnout :

Three percent? I heard that was only because the motherboard would secretly increase FSB just a little.

No - that is when you get the bigger gains.

There are subtle BIOS or board optimisations that can be done to make it more powerful, but they really make a small difference.