AMD Crossfire and WiFi adapter in MSI H97 Gaming 3

[MasterofLego]

I have an MSI H97 gaming 3, and I want to know if I can have crossfired HD 7870s (Id already own both), as well as my D-Link DWA-566, because I read something in the motherboard manual saying that if I put something in the second x16 slot, I can't have anything in either of the x1 slots.

 

[rhysiam]

You have a bigger problem that is your second x16 slot only runs at PCIe 2.0 x4... which is going to be an issue for crossfire.

Plus, according to the spec page: http://www.msi.com/product/mb/H97-GAMING-3.html#hero-specification
Your two PCIex1 slots are disabled with both x16 slots populated, as you said.

In theory you could get an external USB wifi adapter, but I don't think running CFX on a x4 2.0 slot is a good idea anyway.

 

[MasterofLego]

here is a screenshot of the overview page: http://imgur.com/yCuxGpV
which says that it has up to two x16 slots.

 

[rhysiam]

Yes, but it's misleading (unfortunately all manufacturers do this).

If you go into specifications and change it from "Basic" to "Detail", it tells you the following:

------------
• 1 x PCIe 3.0 x16 slot (PCI_E2, supports x16 speed)
• 1 x PCIe 2.0 x16 slot (PCI_E4, supports x4 speed)*
• 2 x PCIe 2.0 x1 slots
• 3 x PCI slots
* The PCIe x1 slots (PCI_E1, PCI_E3) will be unavailable when installing an expansion card in the PCI_E4 slot.
----------

When it says "two x16 slots", it means it has two slots of x16 length capable of supporting x16 cards. The problem is that it only has 4 PCIe 2.0 lanes directed to the second x16 slot.

Unfortunately that's one of the limitations with the H97 (and earlier Hxx chipsets), there's no option for two x8 slots like you get with many Z97 boards.

 

[rhysiam]

Crossfire will technically work with a second card on a PCIe 2 x4 slot, but it will be an issue in some games. You really want a slot running at PCIe 2.0 x8 at least, or ideally PCIe 3 x8 for crossfire.

Nvidia SLI will ONLY work on slots of x8 or greater, the SLI option doesn't show up if you put the card in a x4 slot. AMD don't impose that same restriction so you can actually enable crossfire... but it's questionable as to whether it's worth it.

I have a motherboard that's limited to x4 on the second slot and spent some time researching the impact I'd have going crossfire. I never found any articles with a definitive answer, but the bits and pieces I found suggested that it will have an impact.