I built this PC to serve as a simple home server, so that I can host my own Teamspeak 3 and Minecraft Server. I have already mostly completed this Build in March 2016, but I decided to put it here now.
My ISP gives me a static IP so I considered running a TS3 and Minecraft Server for my friends and me. When I got the opportunity to buy a used Lenovo ThinkCentre M91p SFF for a good price, I decided that this will be the Base of my Server. I got it for 70€ at the time. This computer is running on Windows 7, I had it running on Ubuntu Server for a while, but my friend sometimes want to connect for maintenance, and they are not familiar with commandlines so I put Windows 7 Pro on that machine. I had the Product Key anyways, sy why just don't use it. The Lenovo ThinkCentre came with an i5-2400, 4GB of DDR3 memory and a 360GB HDD.
CPU: The i5-2400 is enough for running a TS3 Server alongside a Minecraft Server. It runs the Vanilla Minecraft Server very smooth and even with multiple players. I was running Skyfactory server for some time and also a Feed the Beast Infinite Server with only some lag in the endgame (huge automated Farms and multiple loaded Dimensions)
CPU Cooler: I bought this from a friend just a week ago, because I am constantly monitoring the temps with HW Monitor. This PC is running in a insulated room in the attic (the rest of the attic isn't insulated). It gets aproximately 50°C in this room on hot summer days. Now in November the temps drop down to less than 0°C. Until now I used the cooler which came with the Lenovo ThinkCentre. This cooler seemed a little better than a Intel Boxed cooler, so I was fine with it. When I saw the opportunity to get a great cooler for a very low price, I said "why not..." and got the C12P SE14.
Mainboard: Its the mainboard of the LEnovo ThinkCentre: This Mainboard features anything I need: A CPU Socket, 4 places for RAM sticks, SATA ports and a gigabit Ethernet Port.
RAM: 4GB came with the Lenove ThinkCentre. I considered 4GB a little less for running a Minecraft Server (especially modded), so I decided to add 8GB of Crucial Ballistix DDR3. I went with the 1600MHz Sticks because there wasn't any Difference in Price.
Storage: I wanted to use a SSD in this build, because I really don't like long boot times. I had this Crucial mSATA SSD from my old Laptop which I didn't need anymore. So got a adapter for around 16€ (a lot cheaper than a 120GB SSD). It starts very fast. I think that I measured about 20 seconds after a clean Install of Windows 7 Pro.
Case: I had the Xigmatek Asgard Mid Tower standing around for some Time from a previous Build which I put into another Case. I would say, that this case is very basic. It is still nice to build in. I lost the 5.25" bay covers. The DVD Drive and the Card reader came with the ThinkCentre, so I pot them in there, because I really have no other use for them.
PSU: I got this PSU from another friend who upgraded his PC and therefore needed a better PSU to drive his AMD FX 9590. So I bought this be quiet! PSU from him. It is more than overkill for this low power build.
I didn't add any temperatures in the Details. In the summer the temperatures topped out in the 80°C range and The temperatures in the little room where the PC is runnig vary a lot over the course of the day. I plan to measure the temps over one day, to see how the differences between ambient and core temperature are.
I hope you like this build and give me some feedback. I am very sorry for any spelling or grammar mistakes, I put this text together in a hurry.