SLI compatibility?

I have been building my own computers for many years now but I have never made a PC with a SLI setup nor have I ever really looked into it... till now. My reasoning was all the bad stuff I heard about driver support, but now I hear great things of the driver support.

So, I built my current PC a little while back (Q9550, 4GB RAM, and a 260 that I replaced with a 1GB GTX 460), but for BF3 (and many of the other great games soon to be released), I plan on building a whole new rig and was originally going to get a 580 but after seeing some benchmarks:

http://benchmarkreviews.com/index.php?option=com_content&task=view&id=614&Itemid=72&limit=1&limitstart=8

I saw that SLI 1GB 460s beat out the 580 in most situations as well as many other high-end single GPU cards. Seeing as how I can get a 1GB 460 for $150-$170 I figured that would be my best bet.

So here is my question, how similar do the cards have to be to SLI? Do they have to be the exact same cards? Like I said, I got my 460 a year ago and I doubt that exact same one can be purchased from Newegg. So if I were to get these:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130570

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130696

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130567

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130571

Would they all be compatable to SLI together? If not, then I guess I am getting the 580. I hope I can get the 'better than a 580' performance for just $150.

Thanks for any and all help.

EDIT: Oh, and my new build will have a i5 2500 for the CPU (might not get the K since I don't plan to overclock), and probab;y 6GB of RAM since 4 is still good enough. I will have a 64GB SSD for Win 7 and BF3 (if it will fit) and a 1TB WD HDD. I'll probably just get an 800w PSU since that should be more than enough for that CPU and whichever GPU setup I got with.

Yes, it doesn't matter what brand it is, just has to be another GTX 460 to get it to work.

Sounds good so far. I would just add that you will need to go either 4 or 8gb of ram, 6gb is triple channel and 1155 mobos only support dual channel (2x2gb or 2x4gb or 4x2gb).

Also SLI gtx 460's will run on a 650W psu just fine so depending on what you have now you may be good.

Cool beans. That's what I thought and I'm very glad I was right. So glad to hear that SLI drivers have improved so much over the past few years. I might as well go on ahead and get the 2nd 460 and put it in my current rig.

Sounds good so far. I would just add that you will need to go either 4 or 8gb of ram, 6gb is triple channel and 1155 mobos only support dual channel (2x2gb or 2x4gb or 4x2gb).

Also SLI gtx 460's will run on a 650W psu just fine so depending on what you have now you may be good.

morgofborg

Oops... I meant to put 8, not sure why I put 6. I just see people going with 12 a lot today and that is just overkill.

I think I'll get the 800W PSU just for when I want to get something after the 460s. It seems like nVidia (and AMD but when it comes to GPUs, like I said, I always get EVGA) has really been getting a hold of making power smart GPUs. The 460 runs with such little power and runs cool too.

So my roommate has a 460 768MB version. I think I'm gonna take his out and try that to see how much my FPS goes up. Might as well use that while I wait till I buy the 1GB 460 and it ships.