as the site you mentioned had this content
2 x DIMM, max. 4GB, DDR3 1333*/1066 / 800 MHz, non-ECC, un-buffered memory, dual-channel memory architecture
4 x DIMM, max. 8GB, DDR2 1066*/800 / 667 MHz, non-ECC, un-buffered memory
Dual channel memory architecture
* The chipset officially supports the memory frequency up to DDR3 1066MHz/DDR2 800. Due to the tuning by ASUS exclusive technology, this motherboard natively supports up to DDR3 1333/DDR2 1066MHz. Please refer to www.asus.com
or user manual for Memory QVL
If you fo through that * commented line you can use 1333 mhz ram ddr3 which is clear.