PCIe Slots and Dual Video Cards

[cosine_omerta]

I'm looking at some motherboards that will support two video cards, and I'm not sure what would be better. The specs say things like (single @ x8; dual @ x8/x8 mode) or (single @ x16; dual @ x16/x4).

With some research I've found this is the way the buses are used and shared. I'm curious which is better when using two video cards? Do I want them to share the bus at 8/8 or 16/4. I probably wouldn't go as high end as a 16/16.

Thanks for any insight!

 

[Aastii]

8/8

8 won't bottleneck any video card, and to be fair, neither will 4 unless you go extremely high end, then it can start getting up there, but even without the bottleneck, it can cut down performance a little, usually only a few %, but still better to cut down as little as you can, and give yourself more scope for future upgrades

 

[Ankur]

8/8

8 won't bottleneck any video card, and to be fair, neither will 4 unless you go extremely high end, then it can start getting up there, but even without the bottleneck, it can cut down performance a little, usually only a few %, but still better to cut down as little as you can, and give yourself more scope for future upgrades

Sorry for posting here, but why does anyone require SLi/Crossfire?
I have seen in youtube that some guys have 3 way GTX 580 SLi
Is it really worth it?

 

[Aastii]

Sorry for posting here, but why does anyone require SLi/Crossfire?
I have seen in youtube that some guys have 3 way GTX 580 SLi
Is it really worth it?

For 2 reasons - a cheap performance gain or bragging rights.

Say you have a 5850 now, it is great for now, but a year from now it will probably be showing its age (a little), but because it is "outdated" they will be going for dirt cheap, so you can buy one and massively increase your performance

 

[CardboardSword]

For 2 reasons - a cheap performance gain or bragging rights.

Say you have a 5850 now, it is great for now, but a year from now it will probably be showing its age (a little), but because it is "outdated" they will be going for dirt cheap, so you can buy one and massively increase your performance

+1

I'd also like to mention that you should aim for a board with PCI-E 2.0 slots. 2.0 offers twice the bandwidth of PCI-E 1.0, so even an 8x slot is still like running a card in a 16x PCI-E 1.0 slot. Even still, the differences are fairly minimal. You would be bottlenecked a small amount by a 4x PCI-E 1.0 slot, but this doesn't make adding another card worthless by any stretch.