ASrock Z77 Pro 3. Why is an Intel based motherboard able to run CrossFire but not SLI?

[thegreydorien]

It is very uncommon to run an Intel chip-set with AMD graphics or visVS an AMD chip-set with Nvidia graphics. (I know they will work OK together just not the norm). So here it is, I bought an i7k Processor with an ASrock Z77 Pro 3 motherboard from a friend (should have done more research on the board) at the time i owned a MSI GTX 680 Lightning and it worked great but as age set in i wanted to upgrade in the way of a 2nd MSI GTX 680 Lightning. Luckily before ordering i looked at the box the ASrock MoBo came in and noticed that it listed CrossFire as a possibility but not SLI. This puzzled me because i hadn't for one second thought about an Intel MoBo designed for an AMD Graphics solution. I did a bit of further research and realized that indeed i could not SLI my 680 using this MoBo. I liked the MoBo and planned to replace it only when i replaced my CPU. I ended up selling the MSI GTX 680 Lightning and purchasing a nice new and shiny PnY GTX 780 Ti Enthusiast Edition. Problem gone, but gees. why make Intel chip-sets for AMD graphics... its like a BMW engine going in a Mercedes .. ugh... getting close to that magical time when student loan money comes and new computer is built.. Honestly though my setup flies, ultra on everything, every option checked and smooth 60fps or more. For 2-3 year old tech this rig flies. CPU is not liquid cooled......but it does have one hell of a heat-sink/fan combo(runs 4.8Ghz 40c )But why the Intel/AMD setup? That is my question. Aren't Nvidia products meant to work better with Intel Chip-sets and AMD chip-sets best suited for AMD Graphics cards? Anyone want to give it a go and answer this for me. Cheers!! find me on FB Dorien Grey

 

[Calvin7]

ASrock Z77 Pro 3
1 x PCI Express 3.0 x16 slot (PCIE2: x16 mode)
1 x PCI Express 2.0 x16 slot (PCIE3: x4 mode)

CrossFireX boards can use a x4 mode slot.
SLI doesn't work in a x4 mode slot.

On better ASRock Z77 motherboards (Z77 Extreme9 for one) an additional PLX PEX 8747 PCIe Gen3 bridge chip is used. It offers solid PCIe 3.0 lanes for PCIe devices and is optimized to support high performance graphics. With this bridge onboard, this motherboard is able to work with dual VGA cards (2-Way SLI/CrossFireX) at PCI-E Gen3 x16 / x16 mode or four VGA cards (4-Way SLI/CrossFireX) at PCI-E Gen3 x8 / x8 / x8 / x8 mode.

 

[terry4536]

When I looked at this post , my answer began with "that isn't correct". That is because from my standpoint building gaming systems it isn't true. The vast majority of Intel "gaming motherboards" support both SLI and Crossfire. But I began to look at Intel processor motherboards in general, and your statement becomes more true.

But that is the problem with your statement. For the most part, the people who are concerned with Crossfire and SLI are gamers plus those needing graphics intensive motherboards. Those gaming motherboards have at least three PCI Express slots. And they tend to support both SLI and Crossfire. The majority of motherboards (of either processor category) are not intended for multi-graphics card use. For example, I would direct you to all of the motherboards that have just a single PCI Express x16 slot. Obviously they are not going to support multi-GPU cards. The next subset of motherboards with two PCI Express x 16 slots typically only support Crossfire. The rest of the motherboards with more than two PCI Express x 16(or x4 , x8) have PLX bridge chips to augment the PCI lanes. These tend to support both multi-GPU technologies.

On the AMD side of things, AMD processor motherboards do tend support crossfire more often. But it it is also true that fewer AMD motherboards have more than one PCI Express x16 slots. Even fewer AMD motherboards support three or more PCI Express x 16(or x4 , x8). But those that do support both Crossfire and SLI.

So, your statement "It is very uncommon to run an Intel chip-set with AMD graphics or visVS an AMD chip-set with Nvidia graphics" just isn't correct. And if you like I can produce many examples in both versions of motherboards.


Intel Motherboards (LGA1151) with 2 PCI Express x 16(or x4 , x8) (tend to support AMD Crossfire)


http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627%20600567584%20600176035&IsNodeId=1


Intel Motherboards (LGA1151) with 3 PCI Express x 16(or x4 , x8) (tend to support both)

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&IsNodeId=1&N=100007627%20600567584%20600165671

AMD Motherboards with 3 PCI Express x 16(or x4 , x8) slots (tend to support both)

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&IsNodeId=1&N=100007625%20600041410




As for the reason that the ASrock Z77 Pro 3 doesn't support SLI but does support Crossfire, that motherboard falls into the category of having two PCI Express x 16(or x4 , x8). It doesn't have the PLX bridge chip to augment the PCI lanes. So there is one PCI Express x 16 (3.0), but the other PCI E slot is only operating at PCI Express X4 (2.0). That is sufficient for Crossfire but not SLI

 

[terry4536]

Here is some more information on the SLI limitation on PCI Express x4. So even with a motherboard that is capable of SLI, you need to leave the other PCI Express slots empty to run multi-GPU in SLI (in general).

https://forums.geforce.com/default/topic/736221/why-limit-sli-to-not-work-on-4x-even-in-a-pcie-3-0-slot-/

 

[Tradesman1]

ASrock Z77 Pro 3
1 x PCI Express 3.0 x16 slot (PCIE2: x16 mode)
1 x PCI Express 2.0 x16 slot (PCIE3: x4 mode)

CrossFireX boards can use a x4 mode slot.
SLI doesn't work in a x4 mode slot.

On better ASRock Z77 motherboards (Z77 Extreme9 for one) an additional PLX PEX 8747 PCIe Gen3 bridge chip is used. It offers solid PCIe 3.0 lanes for PCIe devices and is optimized to support high performance graphics. With this bridge onboard, this motherboard is able to work with dual VGA cards (2-Way SLI/CrossFireX) at PCI-E Gen3 x16 / x16 mode or four VGA cards (4-Way SLI/CrossFireX) at PCI-E Gen3 x8 / x8 / x8 / x8 mode.

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