daehned

It heavily depends on your use-case. If you're only doing some office stuff, you won't notice any performance drops. Gaming could be a bit slower, especially the loading times and if you perform heavy I/O tasks like running a database server you will definitely notice a lower performance and higher response times. Massive I/O tasks in combination with a non-spinning drive (SSD) will experience performance drops up to 30%

Security update against spectre and meltdown for windows 7 had the number 4056897 (KB4056897). It will only install if your antivirus software is compatible. For further information see: https://support.microsoft.com/en-us/help/4073757/protect-your-windows-devices-against-spectre-meltdown

Did you tried to boot the server without the new drives to ensure that everything else is okay?

Some dmesg logs would also be nice to see what the kernel is actually doing under the hood.

I've switched to Linux about 3 years ago. Since I'm not a heavy gamer or so, it wasn't a big deal for me, but I think the follwing might be interesting for some of you. So, it all started with a Windows machine (like every other person out there) that sat under my table quite a while - mostly unused 'cause I live on the countryside in Germany and had literally no usable internet connection back then. My only way to get updates and stuff was to carry my PC to the next city and ask a friend to use his internet connection... And carrying around a full-size tower PC isn't that much fun if you have to go by train. Someday, someone offered me an used MacBook Air (late 2011) and i bought it mostly beacause I had to administrate ~25 Macs at work and my macOS knowledge was very limited at that time. But time changes everything and the company ditched iOS app development completely just a year after that and i got back to my loved linux servers. Linux at work, macOS at home and here and there within my family a Windows machine got a bit anoying to me. That's why I started to switch to Linux, starting with the PC's of my grandma and my parents. After that, my girlfriend at that time also switched to Linux and I totally forgot that there's a MacBook somewhere in my house (I had so many things to do - at work and at home - that I haven't used a Computer at home for month). But someday I got it back in my hands and decided to install Linux on it as well. It was... not so complicated that I thought it would be. In fact Arch Linux runs just fine and with the massive Arch User Repository (AUR), theres a software for every problem you might encounter, e.g the fan control. I thought the fan speed of my MacBook was controlled by the BIOS (or whatever it's called in the Apple universe), but it wasn't. So a few minutes on internet research and I found a neat program in the AUR which does the job. Next thing was the installation of Steam. Arch Linux is not officially supported by Steam but, you gessed it, there is a package in the AUR, and it installed just fine. At that time, my girlfriend and I rediscovered Skyrim on one of her "old" Windows Laptops and I wondered if I could make it run on my Linux-MacBook. As you probably know, there's no Linux version of Skyrim, so Wine was the way to go. Wine is not an emulator, it adds a compatibility layer for Windows based programs into linux which has way better performance than a virtual machine on the same host. My first attempt to install Skyrim with Wine was not successful, so I kept searching. To the rescue came PlayOnLinux, a software which helps you to install Windows software with Wine. And this thing was great. It had profiles for Skyrim on board and downloaded and installed all necsessery dependences. Finally, after hours of work, I was able to start Skyrim, a Windows program, on my Linux powered MacBook Air Buut.. the performance was bad. Really bad. 5-15 FPS was the most i could get out of my Laptop without cooking it. But that doesn't matter, I mean what should I expect from a machine with Integrated Graphics on a i5-2557M. And performance wasn't the matter, the question was not "could I play Skyrim?", it was "could i _run_ Skyrim?" - and the answer is: yes. Conclusion: Linux is a powerful operating system. The shell, graphical desktop environments, the community and the fact that everthing is open source makes it perfect for me. I could decrease battery usage by switching from "normal, resource hungry" applications to console-based ones (I'm reading my mails with neomutt, music play's with sconsify, filemanagement with ranger, etc.), yet could I run popular Windows programs like MS Office if I want to. And even games shouldn't be that much of a problem, if you have the right hardware. Running two vesions of Steam (Linux-native, and Windows version over Wine) on the same machine might seem ridiculous, but hey, it works. And Wine together with the latest graphics driver improvements is getting better and better in the case of performance and resource usage. I assume that there isn't so much performance loss that one might think, so why should you run and maintain a dedicated Windows OS? If you want to switch to Linux, but your favourite Games doesn't exist for Linux, check out the PlayOnLinux Supported Software page, or if you're willing to spend some money, take a look at Codeweavers CrossOver.

Try elementary OS. It will probably match all your requirements, it's beautiful (at least if you like a macOS-ish look), comes with some software preinstalled (but not so much to consider it 'bloat') and if you miss any application, there's an easy to use App Store. In fact, it's so newbie-friendly that even my grandma use it.