Windows Server 2012 R2 Main drive

[Ralms]

Hi there,

 

Im running my home server on Windows Server 2012 R2 and before anyone starts hitting stuff like: Linux is the way to go! or FreeNas is way better. I can tell you: sure, depends on your needs. I have a genuine standard licence and the server is mostly for domestic stuff so its fine.

My doubt is this: atm the C drive is running on a mechanical drive and windows is trashing that thing hard, I mean doing defrags from time to time, etc. I noticed that server 2012 R2 likes to use the secondary drive more than the main one and since this was my first time using windows server, I did the stupid mistake of having the C and D drive be the same physical drive, so that thing is suffering lol

So Im gonna change the C Drive into an SSD that can take that hit easily and split the load. Since windows doesnt seem to use the C Drive for a lot of stuff that we use the server for, File Shares, backups, etc, how important is it to be a very fast drive? 

I was considering a 120GB drive, stuff like: 

Kingston SSDNow V300 (SV300S37A/120G) 61€
Kingston HyperX Fury (SHFS37A/120G) 68€
Samsung 850 Evo (MZ-75E120B/EU) 82€
Kingston HyperX 3K (SH103S3/120G) 84€

The reason I'm asking how fast does the drive need to be and the impact its gonna be is mainly due to price. 

Any ideas?
Thank you in advance.