7 replies to this topic

[Koshadows]

Okay so I have a question regarding the PCI-E slots on a mobo that I'm trying to buy. The asus model will have 1 PCI 3.0 x16 and one PCI 2.0 at x4.

Now i know the x4 will bottleneck a card, but i would like to know how much would it affect that second card if it was in the slave configuration in a crossfire. Any information would be nice, thanks in advance

[LordDeathStrike]

any time you do crossfire or sli you want 2 or however many you are using, matching card slots for the cards. (sli at least can link 3 and 4 cards although the performance gains are abysmal for the price)

[Vulpesveritas]

If it's a low end card, no. If it's a Radeon HD 6870 or above, yes.
Bandwidth bottlenecks do happen.

[Koshadows]

Right, while i understand the hit to performance, any ideas on how much of a hit it would be?

I'm probably looking at crossfiring a pair of 7850s, but I'm only gonna have one for about 6 month

[Oderint dum Metuant]

Personally i wouldnt X-fire into a board with a 4x slot.

16x/16x or 16/8x slots.

[Catamount]

Well if it's PCIE 4x for the 3.0, you're basically talking an 8x slot from the 2.0 generation no?

It seems to me the bottlenecking would be present, but the card would still give most of its performance. Is it still worth doing? No, imo. The loss of performance might be modest, but combine it with microstutter and it becomes non-worthwhile.

Just get a single Radeon HD 7970 instead.

[Koshadows]

aw nuts, there goes my grand plan. Looks like I do have to look for a new mobo instead.
Its only an x4 pci-e 2.0.

The crossfire idea is that i get one 7850 now with the money i saved up and then get another during black fridayish if they have any good deals. Otherwise i think a single 7850 is more than enough to play most of my games and won't set me back more than $260

[bawchicawawa]

Get a board with 8x 8x pci-e 3.0

The difference between 8x 8x and 16x 16x is only a few percent in performance.

And, instead of 1 7850, get 2 7770's.