Does installing 2 NVME drives have any negative effect?

Tutan · 27 May 2021 at 13:55

I have a ASUS TUF Gaming B550M-Plus mothetboard paired with Ryzen 5 5600x and currently a 1TB Samsung PCIe 4 980 Pro NVME drive.
the Motherboard has another free NVME slot,and I'd like to add another drive.

but I've heard having two NVME drives somehow limits/bottle necks the speed/bandwith and is not a good idea,is this true? does having drives in both 2 slots have any cons in any way?

what happnes if I add an identical drive to the second free slot? and what happens if I add a slower rated (for example speed NVME drive to the second slot?

EsaT · 27 May 2021 at 15:00

Standard M.2 slots don't share resources.
Though with B550 being PCIe v3 chipset, paying heavy PCIe v4 luxury doesn't give anything for second drive even in benchmarketing.

But in case of building new PC there's one negative with more than one of any HDD/SSD:
When installing Windows there's zero guarantee that boot sector etc data are put on the drive you actually want the OS.
That often causes situations in which removing/changing non-OS drive makes PC unable to boot into OS.
Hence when installing Windows you should always have only one drive connected. (opticals don't count)

Tutan · 27 May 2021 at 15:22

EsaT said:
Standard M.2 slots don't share resources.
Though with B550 being PCIe v3 chipset, paying heavy PCIe v4 luxury doesn't give anything for second drive even in benchmarketing.

But in case of building new PC there's one negative with more than one of any HDD/SSD:
When installing Windows there's zero guarantee that boot sector etc data are put on the drive you actually want the OS.
That often causes situations in which removing/changing non-OS drive makes PC unable to boot into OS.
Hence when installing Windows you should always have only one drive connected. (opticals don't count)

this MB & my CPU support PCIe v4..and I currently get full speed of this drive.
I only have one storage drive altogether (1TB 980 Pro PCIE 4) and would like to add another one of same spec.but not if there is a performance/speed drawback.

Murphy · 28 May 2021 at 07:22

The B550M-Plus' second NVME slot is PCIe gen 3 so that's going to be your limiting factor.

Hook · 28 May 2021 at 08:53

AMD B550 Chipset :
1 x M.2_2 socket 3, with M Key, Type 2242/2260/2280/22110(PCIE 3.0 x4 and SATA modes) storage devices support

turbot1984 · 28 May 2021 at 09:00

EsaT said:
Standard M.2 slots don't share resources.
Though with B550 being PCIe v3 chipset, paying heavy PCIe v4 luxury doesn't give anything for second drive even in benchmarketing.

But in case of building new PC there's one negative with more than one of any HDD/SSD:
When installing Windows there's zero guarantee that boot sector etc data are put on the drive you actually want the OS.
That often causes situations in which removing/changing non-OS drive makes PC unable to boot into OS.
Hence when installing Windows you should always have only one drive connected. (opticals don't count)

I had that Win 10 install problem, it also went into legacy bios mode as wouldn't read m.2 as GPT, what a faff! Will know for next time

What about adding a third nvme? Does that slow things down? Also got 2 x ssd installed.

Shaolin Chicken · 28 May 2021 at 09:37

I found that my second NVME drive ran slower on the second m2 slot,
it was about 500mb/s slower on the reads, can't remember how much slower the writes were.

Tutan · 28 May 2021 at 20:17

Murphy said:
The B550M-Plus' second NVME slot is PCIe gen 3 so that's going to be your limiting factor.

I see,so if I install a gen 3 NVME in it's second slot,will this affect the speed of my gen 4 drive in any way?

Murphy · 28 May 2021 at 23:31

I can't think of any reason it would, the gen 4 NVME slot (top one) is directly connected to the CPU, as is the top x16 PCIe slot. The gen 3 NVME slot (lower one) goes through the chipset, the chipset connects to the CPU using its own 4x PCIe gen 3 lanes.

Maybe if you were transferring from a +5Gb Ethernet, copying from an external USB 3 drive, and hitting a couple of SATA drives all at the same time you'd see bottlenecking due to them all hanging off the chipset and the link from that to the CPU only being 4x PCIe gen 3 lanes.

Firegod · 3 Jun 2021 at 08:44

Tutan said:
I have a ASUS TUF Gaming B550M-Plus mothetboard paired with Ryzen 5 5600x and currently a 1TB Samsung PCIe 4 980 Pro NVME drive.
the Motherboard has another free NVME slot,and I'd like to add another drive.

but I've heard having two NVME drives somehow limits/bottle necks the speed/bandwith and is not a good idea,is this true? does having drives in both 2 slots have any cons in any way?

what happnes if I add an identical drive to the second free slot? and what happens if I add a slower rated (for example speed NVME drive to the second slot?

Have a read of the manual, it should tell you what will happen. On my Asus B550 Gaming board if you have two m.2 drives (which I do albeit both drives are gen3) it simply disables some of the sata ports. Doesn't alter any pci speeds. So you can be gen4 in m.2_1 and gen3 in m.2_2. But it should definitely tell you in the manual.