HI i just bought a GTX few day ago ... i like performance pretty much ( i had 2900xt before ) . i just made my first 3dmarks at default spec and hit 12 k . ( 11,5 at high res 1600-1050 )
 
I was wondering if it worth it to put another GTX in SLI ??? ill notice it in 3dmarks and Game ???
 
oh , another question !! GTX's sli is better then 3870 CF ?
 
thx you

Hello and welcome to the forums mate this thread will help u:
 
http://www.tomshardware.co.uk/foru [...] sfire-faqs
 
if u play @ 1680x1050 then 1 GTX is enough  
 
Do SLI or CrossFire always improve performance ?  
Not Always , there are some games that dont take advantage of SLI or CrossFire , so you wont see a difference between 2 cards and 1 card in those games , but in games that take advantage of SLI or CrossFire , 2 cards will perform better than one.  
 
Is it really necessary to use SLI or CrossFire ?  
Well , it really depends mostly on the resolutions and games you play , resolutions like 1920x1200 and higher benefit more from SLI or CrossFire than resolutions like 1600x1200 or lower (I dont mean SLI or CrossFire wont be good for resolutions like 1600x1200 or lower , i am just saying that SLI or CrossFire shines in higher resolutions.)  
Also as i said , it depends on what games (with what settings) you play , for example if you just want to play games at good settings (with not everything at maximum settings) then MultiGPU technology isn't needed , but if you want to play with every option at maximum settings, then SLI would help , but again i repeat , resolution is very important.  
Caution: Due to some problems (like Drivers and etc) in some games, a single card (like X1900XT) may beat 2 1900XT in CrossFire mode!  so dont always think that 2 cards will beat one card.
 
Also about the last question, 8800GTX (Single) is SOME TIMES better than  
2 HD 3870 in CF mode (because not all games _as i have talked about it in the FAQ_ support MultiGPU )
So 2 8800GTX> 2 HD 33870

Would depend on the Monitor you’re using and the resolutions you play in... Also what game?
Cause I am pretty sure 8800GTX runs WoW @ 10000000%   lol --> no benefit having 2 cards SLI
 
However it will not do the same for Crysis. --> Absolutely would improve your gaming experience having SLI.
 
Pacman --> not so much
 
You get the idea.
 
Overall you can not go wrong with SLI 2 GTX...... if you have the cash.

The short answer is NO.
 
Use the money saved and buy some savings bonds or a CD.

You need a powerful overclocked CPU to remove bottleneck though, the amount of people I see with sli and a huge bottleneck is amazing.
 
Your quad at stock for example would bottleneck you.

Nope a Q6600 @ 2.4 wont bottleneck it