explain to me please...

[BoB3rt]

.... as i undertsand it CROSS FIRE / SLi is 2 GFX cards running together to improve the quality etc. and this is done with the join across the top of the cards.

so why with later cards do both slots need to be x16 PCIe if you connect the monitor in the card with the x16PCIe slot (if u only have one and the other is x4 or x1) .....

why is the connection at the top needed if 2x PCIe x16 is required?

am not aruging the fact just wondering why.

 

[Bengaboy]

Not too sure myself.

I think its just a way of the 2 conecting directly to each other to maximise performance.

 

[BoB3rt]

yeah , but i was also getting at why both need to be pci-e ?

just planning on gettin a 3870 and then crossfiring them but my second slot is x4 so i cant or it is a waste?

 

[MagicBoy]

It works fine on a 16x and 4x slot. I ran x1950's in this config on a P35 board. The boards that do 8x and 8x are slightly faster but not much.

The cards communicate between each using the crossfire bridge. The PCIe slots are used for power and the usual stuff eg texture data from main memory.

 

[tigerstyle]

it will work fine, for optimum performance both slots should be x16, but it makes a tiny difference! Not worth really upgrading over. As long as your main slot is x16 then the difference is minimal.

And I get what you mean about needing to link the cars and them be in the mobo too, I guess a lot of data is being shifted around there!

 

[BoB3rt]

thanks.
i was kinda gutted thinking it would be a waste using crossfire with my board.

its only for when the card i get (3870 or 3850) starts to beciome dated i will get a second to boost it...

 

[thegoonden]

I'd always assumed the bridge was for timing/syncronisation between the two cards, and that they were both fed with stuff to render, via their respective PCI-e slots.

the bridge doesn't exactly look like something that could handle the full bandwidth a card would need (and even if it did, that would imply that two cards worth of work would be going over the "primary" PCIe socket, one lot for card 1 and one lot for card 2).