SSD form factor, M.2 and Add in card(HHHL)

[Phaaze88]

https://www.tomshardware.com/reviews/best-ssds,3891.html
Take the Samsung 970 Pro/Adata XPG SX 8200 and Intel Optane 905P from that list, for example.
Is one form factor more favorable over the other? My mobo(X299 Prime Deluxe), can accommodate either type. My decision won't be down to these exact models. It's just for a 'spacey' OS drive.

 

[CountMike]

Both are PCIe 3.0 x4 / NVMe so speed potential is same but Samsung is faster because of it's architecture. It's also handier (smaller). PCIe drives are best used with MBs that don't have M.2 slots.

 

[Phaaze88]

Both are PCIe 3.0 x4 / NVMe so speed potential is same but Samsung is faster because of it's architecture. It's also handier (smaller). PCIe drives are best used with MBs that don't have M.2 slots.

My board has one PCIe 3.0 x4 and 2 of the M.2 slots. If I remember correctly, due to the 7820x having some lane restrictions, only one M.2 slot will work.

What about cooling? It appears that the add in cards are easier to cool than the M.2 sticks. Would it be an issue in my case, a Phantom 820?

 

[CountMike]

Only one that had some heat problems is Samsung 960 Evo, I fixed on a cooler for it but this MB has heat sink for it. It's not a concern for desktop computers. One slot for a medium to large M.2 SSD is enough, For other disks HDD or SSD it's cheaper and more practical to use SATA disks.

 

[Phaaze88]

I see.
So no major performance difference between the 2 form factors, only available space and motherboard support.
I'll just go with the cheaper of the 2.
Thanks for your time.