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M.2 -vs- PCIeX4_1 -vs- MPCIe

tackyjan
Level 7
Hello all,

I have the MAXIMUS GENE VII Micro ATX motherboard and I was thinking about getting an M.2 SSD but I was reading the manual for my motherboard and it describes hows different modes for M.2, PCIeX4_1, and mPCIe slots are not mutually exclusive. If you want the fastest M.2 speed, for example, the PCIeX4_1 slot is totally disabled. Here is the table they list in the manual:

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And here are the notes below the table:

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So as you can see, if I want to run M.2 with the fastest setting (M.2 mode = x2) I will loose the mPCIe slot. And it just so happens that the other day I purchased the ASUS mPCIe combo card for my WiFi access. 😮

Does this mean that if I want to run with the fastest M.2 mode I won't be able to get online? Also, Is this normal for motherboard manufacturers to do? To share bandwidth across the various ports with the M.2 port?

I quickly glimpsed at the manual for the ASRock Z99m motherboard wich also has an M.2 slot and I thought I understood them say that, if you enable M.2 "fast" mode on their motherboard it affect some mSATA port and not any on-board slots.

I really hope that it's not just ASUS that does this. If it is, I am going to feel really bad about spending $200+ on an ASUS motherboard.

Thank you,

Jan

P.S. Here is a picture of the MAXIMUS VII GENE motherboard as shown below the table.

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4 REPLIES 4

tackyjan
Level 7
I was just looking at the manual for the ASRock Fatality Z97M board and here is what they say about the M.2 slot:

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And here is a pciture of the SATA Express connector:

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So does this mean for ASRock boards (or at least this one) that using a M.2 drive doesn't affect the PCIe slots?

Thank you,

Jan

Sparax
Level 9
Hi Jan

tackyjan wrote:
Does this mean that if I want to run with the fastest M.2 mode I won't be able to get online?


Yes if want to run the M.2 connection at x2 the mPCIe will be disabled so yes you will lose your wifi connectivity via your ASUS mPCIe combo card

tackyjan wrote:
Is this normal for motherboard manufacturers to do? To share bandwidth across the various ports with the M.2 port?


Yes all manufacturers do it one way or another some opt to sacrifice there pcie connections while others opt to sacrifice there sata connections either way when using the m.2 interface you are going to have to sacrifice something as the manufacturers are limited by the chipset to 8 PCI-Express gen 2.0 lanes that they can allocate to your onboard devices.

tackyjan
Level 7
I don't understand why ASUS decided to sacrifice a PCI slot, unlike ASRock for example, who sacrifice a SATA port. PCI slots are precious on a micro ATX case as there are only 4 (or less) of them.

tackyjan
Level 7
I am also looking at the MSI Z97M GAMING micro ATX motherboard and it looks like they too sacrifice a SATA port instead of a PCI slot.

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Would anyone mind explaining to me why some manufacturers sacrifice SATA and some PCI?

Thank you,

Jan