All rightie, Windows installation on the second SSD drive went without a hitch (probably because I took out the stock SSD first before installing the OS on the one I stuck in the second SSD bay) and now I'm up and running on my new laptop. C is the secondary SSD I stuck into the laptop which is now the primary drive, the Samsung 970 Evo Plus 1TB, while E is the stock SSD that my laptop came with, which also happens to a Samsung, a PM981a 1024GB (1TB) and is now the secondary drive. I have the Evo Plus to be 1st in the boot order, which is exactly what I want. No screen ever came up asking me to select which drive to boot to, so I think this is working properly. See attached.
Normally, Dell laptops don't seem to come with a Samsung drive. They usually come with a SKHynix drive. I guess I lucked out here. On the other hand, I think it depends on the hard drive capacity you order the laptop with. If I had gotten either a 256GB or 512GB instead, I think it would had came with a hard drive from a different brand. I couldn't really find any speed info on the PM981a, but it seems that it's only slightly slower than the Evo Plus I stuck in the laptop. Thus, I hesitated in sticking in the secondary SSD, but as you can see I ultimately decided to do it, just because I think it's a good idea to separate my files in the secondary hard drive and put my games in the primary hard drive.
The most frustrating part was taking the base cover off. In the Dell XPS 9500, it is considerably harder to take off than in my previous laptop, the Dell XPS 9560. I probably spent almost a good hour trying to take it off. I went to buy a pry tool set earlier today to help me get it off. I was almost tempted to take it to my local Best Buy and ask one of the Geek Squad people to help me take it off due to several repeated failures in getting it off, but I was able to finally get it off myself.
So far, all that's installed in both drives is just Windows. So, my question is do you think it's necessary to reformat and wipe out the preinstalled Windows on the E drive? Would anything bad happen if I did? Or should I just keep Windows on it as well? They're both Windows 10 Pro, btw. The plan is to simply install my games on the C drive, while everything else, like pictures, videos, documents, etc will go on the E drive. I might end up changing that to the letter D.
update: ok, I have attached the benchmark results for both Samsung SSDs. First one is the stock SSD that my laptop came with, while the second one is the 970 Evo Plus that I stuck into the laptop earlier today. Wow, the stock SSD is almost just as fast, so technically it doesn't really matter where I install the OS. Oh well, I chose to make the 970 Evo Plus my primary drive even though I'm not going to see much performance gain compared to the stock. So really, the reason for 2 SSDs is just to separate my games from my other files.
update 2: ok, I used the Windows installer and deleted the OS partition on the stock SSD and thus all the free space is back. I'm not sure how I can separate my pictures/documents/videos from the other stuff like games that I want to stick in the primary SSD, the Samsung Evo 970 Plus, from my external hard drive, since I backed up the entire C drive to it before I set up this laptop. The best I came up with is restore all my backup files to the secondary hard drive and then once it's done I can simply move the files I want to the primary hard drive. Is this a good idea?