p45 confusion

Hi

I just wondering if someone could explain like to a child what's so new about this board. I read the article http://www.tomshardware.com/review [...] ,2001.html where they say:
"The ability to run two PCI Express graphics cards http://en.wikipedia.org/wiki/Video_card in x8 mode hasn’t been available from Intel since the days of its 975X chipset. Dual-graphics P965 and P35 motherboards usually relied on x4 pathways for the second slot, starving the second card with a lowly 2 GB/s transfer rate. By allowing its 16 PCI Express pathways to be divided into two x8-mode slots, the P45 Express can now deliver the same 8 GB/s bandwidth to two graphics cards that its P35 predecessor could deliver to only one." ~~this is what i dont get. Apologize upfront but im a noobie and as far as i understand you can run one vga on 16gbs or divide into two 8gbs, so when you do crossfire both vga's will only operate on the half or their performance or am i wrong. what i mean is that one slot can unleash full power or im getting it wrong?? so by comparing let say these three motherboard which one would be the best pick when you think about building new rig?

1.http://www.newegg.com/Product/Product.aspx?Item=N82E16813131284
2.http://www.newegg.com/Product/Product.aspx?Item=N82E16813131235
-why this one is more expensive then formulaII (see below),might be the cause of ddr3 support?
3.http://www.newegg.com/Product/Product.aspx?Item=N82E16813131319
"this one with the new chipset"

by having these three options what would be your pick??

Upfront thanks you for your answers

Regards

ketrab

The most important question is: What do you intend to do with the machine you are building? What resolution monitor will you use? Unless you intend to run ultra high resolutions, there is no reason to use Crossfire or SLI.

Out of the three motherboards you have linked, the lowest priced board cannot do two PCIE channels at 16x.

The ASUS MAXIMUS EXTREME does have two slots at 16x - http://www.asus.com/products.aspx? [...] odelmenu=1

The ASUS RAMPAGE FORMULA is not specified on Asus's page, however Newegg claims two 16x slots - http://www.asus.com/products.aspx? [...] odelmenu=1

While some boards can do two slots at 16x, this fact is mostly an academic discussion in my opinion.

Excerpt from a sticky FAQ in the Graphics forum - "Some Motherboards support Multi-GPU Technology at Dual 16x mode, some support it at Dual 8x mode and some support it at 16x 4x mode, what are the differences?
Well for getting the best performance out of Multi-GPU cards,you need a Motherboard that supports Multi-GPU at dual(Or more) 16x mode like Nvidia 790i ULTRA SLI, Nvidia790i SLI, Nvidia 780i SLI, Nvidia 680i( As i said, NVIDIA 790i ULTRA SLI ,790i SLI ,780i SLI and 680i SLI support 3-Way SLI too),Nvidia 590i SLI, Nvidia nForce4 SLI 16x, ATI CrossFire Xpress 3200,Intel X38 and X48.

Dual 8x is a very good configuration too,it doesnt have alot of difference with Dual 16x and its cheaper too.
Chipests like Nvidia 750i SLI, Nvidia 650i SLI,NVIDIA 570i SLI, NVIDIA nForce4 SLI, ATI Radeon Xpress 200, Intel 975x and ONLY 2 Intel P35 boards(ASUS BLITZ FORMULA and ASUS BLITZ EXTREME) support Multi-GPU at dual 8x mode.
However for cards like radeon HD 48xx series,its better to get a Dual 16x motherboard because it performs better. "
http://www.tomshardware.com/forum/ [...] sfire-faqs <-- Thanks - very much - to Maziar.

Don't worry about Dual 16x Slots.
Rather, Just get a 4870x2 instead of 2 4870s.
Or get a 9800x2 if money is tight and you need a high end solution.

In general the x2 Cards perform better than two cards in CF setup.

If you are looking at a massive setup such as a 4GPU system with Dual x2 Cards, then we are talking huge bucks on the system for Video, PSU etc...

In such a case, I don't think you would be even be looking at the P45 vs X48 board.

And if you were looking at spending that kind of cash, the i7 would likely be the choice.

However, a budget would really help.

[quotemsg=1792558,6,362290~~so it means for this mobo extreme does dual 16x? or it gets dual 8x???[/quotemsg]

Dual 16x, yes; But this is largely an academic discussion - ie, little to no actual real change in performance because the full bandwidth is not utilized. Zen gives good advice in his above post.