Alrighty, so my problem is simple. Does a motherboards northbridge have to be ATi for me to be able to Crossfire 2 ATi cards? I was looking at a MSI 975X Platnium(which is made by Intel, http://www.newegg.com/Product/Prod [...] 6813130051 ) and I need to know if I can use a Crossfire configuration with this.


Thanks!

The "X" does not denote Crossfire support, but the 975X chipset does definitely support Crossfire.

The P965 chipset also supports Crossfire, however some mobos dual PCI-e graphic ports do need a BIOS upgrade for Crossfire to be available.

Also, could I do SLI if I ever changed to Nvidia on the same motherboard?

Thanks guys!

No. As of now SLI requires a motherboard with an nVidia chipset. Supposedly there have been some conversation between nV and Intel to support SLI on Intel chipsets but so far you can't.

I do think there were/are hacked drivers to allow SLI on non-nV motherboards for the GF7000 series but none I've heard of for the GF8000 series.

No. As of now SLI requires a motherboard with an nVidia chipset. Supposedly there have been some conversation between nV and Intel to support SLI on Intel chipsets but so far you can't.

I do think there were/are hacked drivers to allow SLI on non-nV motherboards for the GF7000 series but none I've heard of for the GF8000 series.

Ah, well I'm thinking of using ATi's 2900 for my new computer anyway. I probably won't use Crossfire, but it is good to know if I can if I want to.

This is not just a "good-to-know" issue. It will affect your choice in motherboards. P965 based boards are often the best bang for the buck with Conroe builds. There are also models with dual PCI-E slots. The problem is that the 2nd slot in these boards runs only 4 lanes to the northbridge, not 8 or 16. This makes an otherwise great board choice a poor one for those who want future crossfire support. P975 and ATI3200 boards offer crossfire support with 8 lane support on both cards. This is much better.
So, how important is that "good to know" for later?

This is not just a "good-to-know" issue. It will affect your choice in motherboards. P965 based boards are often the best bang for the buck with Conroe builds. There are also models with dual PCI-E slots. The problem is that the 2nd slot in these boards runs only 4 lanes to the northbridge, not 8 or 16. This makes an otherwise great board choice a poor one for those who want future crossfire support. P975 and ATI3200 boards offer crossfire support with 8 lane support on both cards. This is much better.
So, how important is that "good to know" for later?
Another thing with P965 boards is that it appears that they disable their x1 PCIe slots to redirect those lanes to the second graphics card when it is installed, which is not good if you happen to have something plugged into them. I chose to get a 965P board (the DS3 was on sale last week) so that I'm not tied to either graphics vendor for now. Coming from a P4 with an AGP 7800GS I'm sure a single 8800GTX or X2900XTX will seem fantastic in comparison. The most appealing crossfire chipset coming out seems to be the Intel X38 due in Q3 this year, which I think supports x16 to both graphics cards. But at the current pace of technology, 1 GF8800GTX > 2 GF7900GTX in SLI, and hopefully 1 X2900xtx will be better than 2 X1950xtx in crossfire, so you might want to just upgrade your whole card when you don't find the 8800 or X2900 adequate any more.

As far as I'm concerned, the ONLY reason that SLI or Crossfire would make sense is if you wanted a pair of the absolute BEST cards. This puts the $$$ out of range for most folks. Anything less just does not make sense. How many people have a 2-3 year old system and think that a pair of 6800s will give the best bang for the buck? Its always better to put $$$ into a single higher end card. Troll bait anyone?

Isn't that what I said? If not then it is what I meant to say and it may have been worded poorly. Certainly not trying to troll.
Maybe I should have said (edits in italics) to be clearer:

I didn't think so but it sounded pretty spiffy till you dropped the bomb on it.

Sorry. I wasn't calling you a troll. It's just that so many folks on this forum seem to think that SLI is critically important. IMO it is virtually useless except for a very few people in a much higher social class than most of us, including me.

The troll bait comment reflected my expectation to be thoroughly trounced on by saying that SLI is just no big deal...

Sorry, my bad . I actually thought about it later and wondered if that was what you meant (even had a person or two in mind you might be referring to). Just panicked at fear of being called a troll. I agree with you about SLI/Xfire for the record, but wouldn't object to somebody using it if that's what they want to spend their $ on. Me, I'm saving up for a Ferrari (Yeah I'll have to forgo a LOT of SLI setups to pay for that).

So a P975 would be the best deal if I wanted to upgrade to Crossfire later? I don't have all of my money now, but later, instead of buying a X3000XTX(for instance), I'd get another X2900XTX.

Yes, for Crossfire an Intel P975 or an ATI 3200 because of the dual 8 lane PCI-Ex16 slots.
I still would not do it that way though...