m.2 mb query

daveheath1888

daveheath1888

daveheath1888

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hi need some advice , doing my first pc build and thinking about connecting 3x m.2 to my motherboard which will be MSI b850 edge ti, in the specs it says :

M.2_1 Source (From CPU) supports up to PCIe 5.0 x4 , supports 22110/2280 devices
M.2_2 Source (From CPU) supports up to PCIe 5.0 x4 , supports 2280/2260 devices
M.2_3 Source (From Chipset) supports up to PCIe 4.0 x2 , supports 2280/2260 devices
M.2_4 Source (From Chipset) supports up to PCIe 4.0 x4 , supports 2280/2260 devices

so the first 2 slots seem fine but the 4th slot seems faster than the 3rd slot so do i put my 3rd drive in slot 4 and if so what are the speeds going to be like "from the chipset" compared to the "from cpu".thanks.
 
Have to agree that any difference is mainly theoretical or only in benchmarks.

Looking at the block diagram of that board:
BrfOnAB.png

(From page 66 of the manual: https://download-2.msi.com/archive/mnu_exe/mb/MPGB850EDGETIWIFI_English.pdf )
The shared bandwith (the whole chipset shares x4 PCIe 4.0) might play role if copying - for example - from/to the USB 3.2 20Gbps ports to the chipset NVMe drives.

As an aside since AM5 CPUs (the non-APU ones) are x28 PCIe with x4 to the chipset, then AMD could release a future chipset where the x4 to the chipset was PCIe 5.0 rather than the current PCIe 4.0. That would improve things for NVMe slots 4 and upwards. Most likely such a change - maybe for Zen6? - would make idle and active power worse though. Faster PCIe speeds are not free. While current rumours suggest even Zen7 will be AM5 - due mostly to DDR6 being projected to be far too expensive in that timeframe - AMD could offer PCIe 6.0 as an option for Zen6 or Zen7.
 
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daveheath1888 said:
hi need some advice , doing my first pc build and thinking about connecting 3x m.2 to my motherboard which will be MSI b850 edge ti, in the specs it says :

M.2_1 Source (From CPU) supports up to PCIe 5.0 x4 , supports 22110/2280 devices
M.2_2 Source (From CPU) supports up to PCIe 5.0 x4 , supports 2280/2260 devices
M.2_3 Source (From Chipset) supports up to PCIe 4.0 x2 , supports 2280/2260 devices
M.2_4 Source (From Chipset) supports up to PCIe 4.0 x4 , supports 2280/2260 devices

so the first 2 slots seem fine but the 4th slot seems faster than the 3rd slot so do i put my 3rd drive in slot 4 and if so what are the speeds going to be like "from the chipset" compared to the "from cpu".thanks.
Click to expand...
That's a nice motherboard but it's expensive and I'm pretty sure you'll never really need PCI-e gen 5.

You could get a pretty good motherboard for £150 and not notice the difference.

If you need that many M.2 slots, you could get an M.2 expansion card in the future.

Do some more research, look at some reviews and make sure that it's the right part for your needs before you spend the money.
 
I could be wrong but I thought the NVMe only runs at X2 if the PCIE 4.0x4 slot was occupied due to bifurcated lanes.

Look up Ronin Wilde on YouTube, he has some videos showing the lane distribution and bifurcation on a lot of B850 and X870E motherboards.
 
sastusbulbas said:
I could be wrong but I thought the NVMe only runs at X2 if the PCIE 4.0x4 slot was occupied due to bifurcated lanes.

Look up Ronin Wilde on YouTube, he has some videos showing the lane distribution and bifurcation on a lot of B850 and X870E motherboards.
Click to expand...
It is really hard to get the definite answers on that. That MSI block diagram is a start but it says nothing about lane sharing.

ASRock to usually have a better block diagram which shows that. Some Asus board have similar but not all and far harder to find AFAIR.

It is all rathee complex and seldom clear. That monster motherboard spreadsheet may list this but while those kind of things and some of the shopping comparison sites are handy for filtering, I'd always look for confirmation on the manufacturer's website.
 
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