slowly building an i7 920 system bit by bit and looking at the memory available im confused 
Would it be better to go for:
Patriot Viper 6GB (3x2GB) DDR3 PC3-12800 (1600MHz)
or
Corsair XMS3 6GB (3x2GB) DDR3 PC3-12800C9 (1600MHz)
or
OCZ Obsidian 6GB (3x2GB) DDR3 PC3-12800C9 1600Mhz
The OCZ is on this week only and £10 cheaper than the other 2 but from what I can gather it doesnt supprt extreme memory profiles (XMP) for the gamers choice what you rec i buy?

Would it be better to go for:
Patriot Viper 6GB (3x2GB) DDR3 PC3-12800 (1600MHz)
or
Corsair XMS3 6GB (3x2GB) DDR3 PC3-12800C9 (1600MHz)
or
OCZ Obsidian 6GB (3x2GB) DDR3 PC3-12800C9 1600Mhz
The OCZ is on this week only and £10 cheaper than the other 2 but from what I can gather it doesnt supprt extreme memory profiles (XMP) for the gamers choice what you rec i buy?