Best computer for calculating things: http://www.top500.org/system/177975

CPU+Cooling: i7-3770k @ 3.5ghz (I hate OCing) & CM Hyper 212+ (For low temps)
He hates OCing yet he buys the unlocked (K) version. Makes sense.

RAM: 16GB Corsair Vengeance DDR3 @ 1600mhz
There's memory faster than 1600MHz. (Although the difference can not be noticed.)

GPU: MSI Lightning GTX 680 @ factory OC settings Got this card to take advantage of the 3D from my monitor.
I believe the HD7970 is a little bit better.

HDD(s): Samsung 840 250gb SSD for Windows + main programs & games.
Depending on the amount of data on his SSD, it will lose performance overtime.
Also, the Samsung Pro 128GB SSD version is faster than the 250GB version.