Is Crossfire With x16/x8 OK?

[Pedroc1999]

So for my next build I want it to be 'Crossfire Ready' incase i want to upgrade in the future. The motherboard in question is the MSI 970A-G46, it has x16 for the main GPU and a x8 for the second. What would be the realworld loss in FPS compared to a x16/x16 configuration

 

[RaistlinZ]

Practically nothing. I think HardOCP did an article that showed only a 1-2% performance loss.

 

[Pedroc1999]

That is good news as i just replanned my whole build because of a footnote stating 'x4' on the last mobo i was viewing...

 

[3DVagabond]

Keep in mind that current graphics cards are pcie3. AMD boards are still pcie2. That's 1/2 the bandwidth of a pcie3. x8 is 1/2bandwidth again. Now you are saying x4. That's getting a bit low @ 1/8th the current standard. I'm sure there's a review that has tested it if you can find one. Off the top of my head I'd say you'll suffer ~10% lower performance at pcie2 x4 compared to pcie3 x16 with a top range card.

 

[Pedroc1999]

Yes thats why i moved from that old one and onto this new MSI one that offers the x8 as well as x16

 

[3DVagabond]

Fair enough. I just wanted to be sure we were all on the same page.

 

[Pedroc1999]

Yes i understand. What would be the realworld fps loss in question with pcie 2.0 and 3.0

 

[lehtv]

Techpowerup: Ivy Bridge PCI-Express Scaling with HD 7970 and GTX 680

The importance of PCIe 3.0 is somewhat greater with multiple graphics cards (HardOCP)

 

[Pedroc1999]

I am talking about single card performance now. What would a 2.0x16 compare to a 3.0x16 in terms of FPS

 

[lehtv]

I just posted the link that answers that.

 

[3DVagabond]

Minimal. One or two percent with a 7970.

 

[jacktesterson]

Yes, works perfect. I had a pair of 7970's on my board (x8/x8) before I sold them. Realized I'm not a serious enough gamer to warrant needing that power, so I downgraded and now game on a TV.

x16 / x4 even has little impact most of the time.

 

[Pedroc1999]

Sorry didnt see it... Well a 1% improvment is not going to put me off AMD tbh. But i thought the cfx bridge would compensate for the lack of bandwidth

 

[lehtv]

Nah, the CFX bridge is there just so the cards can communicate with each other

 

[Pedroc1999]

Ok. Well anyway a loss of upto 3% percente is nothing that really intersets me tbh

 

[PrincessFrosty]

There's not much difference with the current generation of cards, as other people have said, tests show it to be just a few percent, not worth the cost of an upgrade to a motherboard that supports x16/x16

It also depends on what cards you're using, if you're using mid range cards there's probably zero difference.

 

[Pedroc1999]

Ok great to know!