Power Supply – $140 - Corsair 850 Watt Gold Rated PSU.
Motherboard – $95 – ASUS M5A97. This motherboard has two of the 16x PCI-e slots and two of the 1x PCI-e slots. All four slots can be used for mining GPU’s. If it is out of stock, this one or this one are good alternatives.
GPUs – $600 (3x $200) – AMD Radeon R9 270 - If the R9 270 is out of stock, the R9 270x costs just a bit more for slightly more hashing power and will still work with everything else in this setup. For specific configurationdetails...