I'm going to discuss a server model that I've worked on frequently the last few days, and that would be the Dell PowerEdge 1950. This is a 1U unit, two CPUs, two 3.5” or four 2.5” hard drive bays and 8 RAM slots. Depending on which generation you get, you can equip them with single, dual, or quad core CPUs. The G1 and G2 machines can take up to 32GB of RAM, and the G3 will go up to 64GB. Wait. I just typed 64GB. As in 64 GIGABYTES. My first computer had 64 KILOBYTES of RAM in it. I need a quiet moment, excuse me.

 

Okay, continuing onward! The 1950 is capable of handling SAS or SATA hard drives using a SAS-5, -5i, -6 or Perc 5 or 6 RAID card. That will allow you to use either just a bunch of disks, RAID 0, 1, or 5.

 

If you just need raw CPU power, you could fill a rack with 1950s to have a pretty dense arrangement. The 1950s can be had with PCI-X or PCI-E risers, so if you want, you could look into putting video cards to use GPUs for number crunching.