The two considerations:  the faster the drive, the hotter it will run, and there's no clearance inside this system for a heatsink on the SSD.  The other consideration to pay careful attention to is the drive height -- many 2T drives are appreciably larger than single-sided 1T drives.  If you install a drive with more height, it may not clear the case cover. All of the above applies only to the XPS 9310 clamshell -- not the 9310 2-in-1, which despite the similar name is totally different inside and uses a soldered-in SSD that cannot be upgraded.   There are any number of reliable manufacturers of SSDs -- Samsung, WD, Crucial, etc. Given the low power nature of the CPU in this system, I would not look toward pushing the performance envelope on the SSD -- you could well wind up with too much heat inside the system, and there's little margin for cooling in a system this thin and lightweight.  
hi, guys,    i am prasad from india. i brought dell xps 9310 laptop. i am planning to upgrade my nvme . presently this has 1tb. planning to go with 2tb. i have few questions. 1. can i buy pcie4.0 nvme ? the reason i am  thinking about pcie4.0 is  faster data speeds. if yes, please suggest the best brands. Thanks in advance.   Regards. prasad    
dell xps 9310 nvme upgrade