Hello, I am building new PC and I would like to get some opionions. I managed to get 2x 5850 really cheap and I started building my new pc with it. Could you recommend me some motherboards and PSU? I am thinking of i5 2500 or some Bulldozer. I am not going to oc this stuff, I will use no ssd as well (cavial blue 1TB- no money for black version).

greetings

Well, Bulldozer isn't out yet, so that may make that decision a bit easier. You can get AM3+ motherboards now that will be Bulldozer compatible, and stick a cheaper AM3 CPU in there, but then your just more or less wasting the $100 on the CPU that you'd only use between now and then.

You kinda need to nail down which CPU you want to use though, because that will be the deciding factor for your motherboard.

I'm going to warn you, though:
If you can't afford the upgrade from Caviar Blue to Caviar Black, you really can't afford to do Crossfire. The motherboards for x8/x8 (let alone x16/x16) cost more than normal, sometimes significantly more. Your going to need a bigger power supply to drive it all, and that will add a little bit of money. And your going to need a well ventilated case, with good fans - and that will add a good bit over your standard case.

There are a lot of "hidden" costs when going with SLI/Crossfire, and the video cards are only one part of a much larger equation. You really do need to start from the ground up with multi-GPU's in mind, and it takes a better motherboard, a bigger case, and a bigger power supply, more heat dumped into your room, and more power from the socket to drive up your electric bill, to get it to work well.

Now, I'm not trying to tell you what to do with your money, if you want to play with Crossfire, by all means. However, if it were me, I would try to eBay/Craigslist one of those 5850's, and use the cash from that to invest in the PC I made with the other 5850 - you'd see a lot more bang for your buck if you do upgrade to that Caviar Black/SSD and make sure you have a solid everything else (or sell them both and get a single 6950), than you would if you just shoehorn an extra 5850 into a mediocre PC.

I'm hoping that he picked up a pair of the Sapphire one when New Egg had them for $140.  Bulldozer isn't out yet.  Ideally, you'd want x16/x16 PCI Express bandwidth for CrossFire, but x8/x8 will work.  You don't want one of the x16/x4 motherboards.

If you're getting a Core i5 2500 and leaving it at stock speeds, then this should work pretty well for you:

http://www.newegg.com/Product/Product.aspx?Item=N82E16813128488

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For the power supply, you're going to need lots of power and lots of PCI-E power connectors.  A 650 W power supply should be adequate, but a lot of power supplies in that range don't offer the four 6-pin PCI-E power connectors that you need.  This one is pretty good, and does:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817207014

Theroetically, if a power supply offers two 6-pin and two 6+2-pin connectors, that's enough to hook up 600 W worth of video cards alone.  That's not safe on a 600 W power supply, so a lot of 650 W power supplies don't have the connectors for it.  But two video cards at 151 W each is fine, and it seems that XFX assumes that you'll know better than to try to run, say, a pair of GTX 580s in SLI on the power supply and fry it even though the connectors are there.

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I'd argue that if you can't afford a WD Caviar Black, then you can't afford Sandy Bridge, either, let alone CrossFire.  I don't know where you're looking for that WD Caviar Blue, but on New Egg, the 1 TB version is $60, and for $61 you could have a 640 GB WD Caviar Black.

http://www.newegg.com/Product/Product.aspx?Item=N82E16822136319

Even if you think you need 1 TB of capacity and won't pay for a Caviar Black, at least a Seagate Barracuda 7200.12 is faster than the WD Caviar Blue, and the same price:

http://www.newegg.com/Product/Product.aspx?Item=N82E16822148697

thx for help, I think I reconsider some things