questions about M2 NVMe

[Strainer]

Hello,
I have few questions about M2 NVMe disks. I have processor Intel i5-6600k a and graphic card Asus GTX 1070 Strix. These are in motherboard Gigabyte Z170X-Gaming 3 - https://www.gigabyte.com/uk/Motherboard/GA-Z170X-Gaming-3-EU-rev-10#ov
If I understand it well, in this case, there are 16 PCIe lanes for graphics cards directly to processor and chipset have 20 lanes for disks and everything else, so it can't happen, that connecting any disks into M2 slots could limit graphic card and take away lanes from it?

And second question is specific for this motherboard. This board have two M2 slots, named M2A_32G and M2D_32G. In manual on page 17 - http://download.gigabyte.eu/FileList/Manual/mb_manual_ga-z170x-gaming3_e.pdf is sheet, which SATA ports stop working after connecting different M2 SATA/PCIe(NVMe) disks. If I put M2 NVMe disk into top M2D slot, it would run only at x2 speed instead of x4 on AHCI mode (see Note at bottom)? According to these sheets, it seems that it would be better to connect disk into bottom M2A slot (unlimited speed and all SATA ports are working), but this slot is placed right behind heat spreader of graphic card and I don't think that it's smart idea, taking in mind how much heat M2 disks produce. Does it affect function, performance, booting etc. in which slot is M2 disk placed? How can I assure/verify that disk/graphic card runs at 4/16 lanes and nothing limits them? In manual there are sheets for AHCI and RAID, does it make sense to set RAID, if I don't run any RAID array? And personal note - why is such a difference in both M2 slots and why is better one in worse location? Thanks for your answers.

[Strainer]

Looking at that sheet.. M2 NVMe disk would be slowed down to x2, only if there would be connected disk in SATA Express connector? If I have M2 NVMe disk in top M2D position and normal SATA SSD disks in SATA ports 4 and 5, then everything should run at full speed?

[shadowsports]

Greetings,
You are on the right track.  Use the charts to determine which resources will be available depending on the hardware configuration you choose.   

[Strainer]

Yeah, thank you. Looks like I got it figured now and that sheet makes sense.

SATA Express needs 2 PCIe lines. That's why for x4 speed for M2 disk, SATA ports 0, 1, 2, 3 (two SATA Express ports) can't be used.

Just wondering what is disabled, if I connect M2 disk into second M2A port. Or it doesn't share lanes with anything?

[shadowsports]

Yeah, thank you. Looks like I got it figured now and that sheet makes sense.

SATA Express needs 2 PCIe lines. That's why for x4 speed for M2 disk, SATA ports 0, 1, 2, 3 (two SATA Express ports) can't be used.

Just wondering what is disabled, if I connect M2 disk into second M2A port. Or it doesn't share lanes with anything?

The M2A_32G is the preferred connector ias you lose the least number of resources using it.  However if you populate the MD2 and use RAID, your x4 m/2 devices only operate at x2 speeds.  This is the trade off.

[Strainer]

I have already everything installed.

In top M2D slot (for better cooling), I have M2 NVMe Samsung 960 EVO - 250GB

And in SATA port 4 is connected Crucial MX500 - 500GB and in port 5 is my older Kingston HyperX 3K - 120GB. I don't need more drives, so this is enough a it doesn't limit me.

Everything works as it should. Speeds are OK. There are 4 lanes for M2 NVMe (checked in CrystalDiskInfo) and 16 lanes for graphic card (checked in GPU-Z).

[shadowsports]

Thanks for the update.  Many are faced with this type of cooling challenge.  If you have the resources you need, this is all that matters.

[onesolo]

As you can see on my signature, my SSD as not face any slowdown. SSD Samsung utility says that the ssd is in PCIex 4x link and from benchmarks there's no slowdown even when the 2 nvidias are working.

[BrianT]

Can I jump onto this thread if possible as I'm struggling to get my head around what I can and can't connect to the same MB.
I have a 500gb Evo 960 in M2A and a 1tb Evo 970 in M2D my boot disk is a 250gb ssd in SATA port 5.

Are the other ports now no longer usable and is the boot disk in the right port?

there was a time when this all made sense to me but the grey hair appears to have sucked the life out of my brain! 

Apologies if I shold have started a new post but it did seem relevant
Regards
Brian

[shadowsports]

Hi Brian,
You can use the charts in your User Guide.  They outline available resources, performance and what is lost depending on slot population or connection.  With both slots populated, you lose a few SATA ports and x4 support if I remember correctly. 

[BrianT]

Hi Brian,
You can use the charts in your User Guide.  They outline available resources, performance and what is lost depending on slot population or connection.  With both slots populated, you lose a few SATA ports and x4 support if I remember correctly.

Thanks for the reply, unfortunately it's the charts I can't get my head round  I know I'm using AHCI and not raid but for the life of me the more I look at the chart the more confused I get. I'll keep looking and try plugging and unplugging and see what I get

[shadowsports]

You have both m.2 slots populated and an SSD connected to SATA_5.

What board do you have?

[BrianT]

It's the GA-Z170X-UD3.
Thanks for your help

[shadowsports]

It's the GA-Z170X-UD3.
Thanks for your help

AHCI Mode:
x4 m.2 Drive populated in M2A - All SATA ports SATA3_0~5 are available

x4 m.2 Drive populated in M2D - SATA ports SATA3_4~5 are available and m.2 operates at x2 speeds.

[BrianT]

It's the GA-Z170X-UD3.
Thanks for your help

AHCI Mode:
x4 m.2 Drive populated in M2A - All SATA ports SATA3_0~5 are available

x4 m.2 Drive populated in M2D - SATA ports SATA3_4~5 are available and m.2 operates at x2 speeds.

Thanks that explains it better.  So basically if I populate both M.2's then I can only use SATA 4&5 and which will slow down the M2.s?