Crossfire

Google is your friend

http://ati.amd.com/technology/crossfire/index.html

This is either under the link you already have or something extra http://ati.amd.com/technology/crossfire/howitworks.html

Mactronix

SLI/CROSSFIRE FAQs:

http://www.tomshardware.co.uk/forum/245454-15-crossfire...

Cool. It seems to me like CrossFire is better than SLI in general, is that true? Also, there's support for Intel P35, is that a good chipset?

To that... im going to say yes.

I was thinking about going cheap and getting a 2600XT and maybe adding another or a higher end card later. Anyway, how much of a performance difference is there between the 256MB GDDR4 and the 512MB GDDR3? (THG doesn't have both on their charts, and I don't think they have the latest drivers.) I can put say a HD 2600XT with a HD 2900, right?

Bump, sorry.

Nope. You can only put 2 cards in crossfire which have the same core, which means that you can't crossfire a hd2600 and a hd2900. You CAN crossfire the cards if they are the same type, but have different memory amounts, but the extra memory on the second card would not be used.

It is always better to get 1 high end card than crossfire 2 mid-range cards performance wise,a dn 1 high end will be cheaper than 2 mid range cards, but i suppose it depends on your budget on what you can afford at the time.

There is a chart showing which cards can be crossfired with each other, i'm sure someone here has a link of you can prolly find it with a little searching on google.

Crossfire scales a lot better. a LOT.

I would not crosssfire 2 2600's and no you cant mix cards unless you want 1 card to do physics (which seems to not be happening)

honestly if you want crossfire only get it on the top of the line cards you can get else there is little point.

I had intended for the 2600XT to be the physics card when I add a higher-end card next summer. Maybe there will be some more support by then. What about a multi-monitor config? Can I use it for physics and for an extra monitor?

Do you think the 2900's will drop down to <$250 by Christmas?

A few Golden rules about Crossfire or SLI:

A single, faster card is better/more cost effective 95% of the time. Don't buy 2 lesser cards like 2600's and think they will outpace a single 2900. The single 2900 will be better. Buy 1 -2900 now, and when you have the cash, add another later. Don't buy 2 lower or midrange cards and immediately throw them in Crossfire or SLI, again the money is better spent initially on a single high end card.

Use 2 of the same identical cards. If you use a slower card in the pair, the faster card will default to the speed of the slowest card.

If you get 2-256meg cards, you will not have 512 meg of usable memory. You will still only have 256 meg of available memory for the frame buffer. If you want to play a game that needs 512 meg of video memory, EACH card must have 512 meg.

I knew most of that, but thanks. I hope the 2900 prices go down.

ATI is releasing 2 more cards in november - they will have less performance than the 2900, but because they lost the 512bit memory interface for a 256bit one (they don't need all the memory bandwidth anyway) they should cost significantly less, making them a great buy (hopefully).

As to multi-monitor and physics, no-one knows what options you will have if you dedicate a card to physics monitor support wise, i'd guess the main card can still output 2 signals as tecnically it won't be in crossfire. But we can't tell until ati finish their drivers for it.

Well, if they're close to the 2900's and more affordable, they've got my buy.

Is this motherboard good?: http://www.newegg.com/product/product.asp?item=N82E1681...

Seems good to me, although 1 slot runs at X4. Are there any others you would suggest? (Must have a crossfire compatible chipset and >=2 PCI-E x16 slots. A <=$150 Price tag would be preferable.)