X16 and x4 slots

Its recommended that if you are going to use a single card,then put in the first PCI-E Slot.
However if you want to use 2 cards on it,then they will run @ 16x4x which won't perform well(compared to dual 8x/16x)

Technically, you can run 2 cards in that board in CF. However the second car will be severly limited as it is using x4 electrical AND it runs through the chipset at the old PCIe 1.0 transfer rate of 2.5GT/s (half of PCIe 2.0).

Should have said 2 AMD cards. Nvidia will not certify its cards for SLI on x16, x4 slots.

okay,let me start off saying thanks for the fast replys   I am not,by any means,a tech. I am a gamer. I play all of the quake games and am getting into cod mw2. I baught a pc combo kit that had that mobo and an intel i5 duel core @ 3.33. I went and got 2-geforce gts 250's @ 1gig each and want to run them at full speed so what mobo do you recommend for the i5 and windows 7?

okay so ur saying just get a mobo that supports the intel i5 and windows 7 and that is pcie 2.0 x16?

I should have added one other detail before, too. AMD will let you run their cards CrossFired in a x16, x4 - but Nvidia will not certify boards for running SLI that are x16, x4 because of the poorer performance/experiense the user will have.

I would look for a mobo with the P55 chipset that is CF and SLI certified because if it is certified CF and SLI then it will have two PCIe 2.0 x16 slots that, when both are populated, run at x8, x8. So to be safe look for:
1. P55 chipset
2. CF and SLI certification
3. Two PCIe 2.0 x16 slots that run in x8, x8 when both are populated

What is the specific video card you want to put in crossfire? If it is not very high end, it can run in X16 x4 with only very small performance hit. And what is your monitor resolution? It is better to have a single good video card match to your video card rather than pursue crossfiring or SLI on an X16 x4 motherboard.

I am going to use 2 geforce gts 250's @ 1 gig each......but can return and buy 2 new cards that u think might be better than the 2 I chose
I am in no way a tech just a gamer that is trying to build a gaming machine to play q3,q4,q5 and CoDmw2. I bought a pc combo kit from newegg.I really want to run 2 cards so help with the deciding of cards and mobo....thanks.

Looks like your mobo does not support SLI afterall based on what I see in newegg where there is no mention of it.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
What is your monitor resolution? And what is your choice of processor too?

i have an LG 23" lcd hd mon. and I have the intel i5-660

What is the native resolution? It looks like this: 1920x1080 or 1680x1050?

1920x1080 is the res.....sorry it took over a year to respond was a lil tied up

It's getting close to 2 years. Did you run your 2 geforce gts 250's in x16, x4 CF? How are they working for you?