Depends on what you need, and what system you are putting it in.
What motherboard and CPU would these being paired with?
Heres my build ^^
Intel i7 2600k
Asus Maximus Extreme-Z
GTX 580 Lightning Xtreme (OC)
WD 1TB 7200rpm drive
Coolermaster Silent Pro Gold 1000w
Windows 7 64 Bit