Does installing 2 NVME drives have any negative effect?

[Tutan]

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?

 

[Tutan]

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.

 

[Tutan]

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?