I made a Minecraft server with a Pi 2. I overclocked it with raspi-config to something like "Medium". I intend to keep it running 24/7 without a case. Do I need a heat sink and a fan in this situation? If so, please, if you can, reference me to some heat sinks and fans I can use with a link. Thank you.
The Pi does not require cooling (fans, heat sinks etc.). The only time it would need some form of cooling are if it is being overclocked to unrealistic limits (far betynd what you can configure via raspi-config), or if enclosed in something which prohibited nearly all air flow (e.g. inside a teddy bear).
From the Raspberry Pi Foundation's FAQ:
- DOES IT NEED A HEATSINK?
You should not need to use a heatsink, as the chip used in the Raspberry Pi is equivalent to that used in a cell phone, and should not become hot enough to need any special cooling. However, depending on the case you are using and on the overclocking settings, you might find a heatsink to be advantageous. Of course, if you just like the look of a heatsink, you will not hurt the Raspberry Pi by placing an appropriately-sized heatsink on it.