Asus P5K64 WS - Manual (Page 40)

2-14 Chapter 2: Hardware information
• If you install four 1 GB memory modules, the system may detect less than
3 GB of total memory because of address space allocation for other critical
functions. This limitation applies to Windows Vista 32-bit/Windows XP 32-bit
version operating system since it does not support PAE (Physical Address
Extention) mode.
• If you install Windows Vista 32-bit/Windows XP 32-bit version operating
system, we recommend that you install less than 3GB of total memory.
Notes on memory limitations
• Due to chipset limitation, this motherboard can only support up to
8 GB on the operating systems listed below. You may install a maximum of
2 GB DIMMs on each slot.
64-bit
Windows XP Professional x64 Edition
Windows Vista x64 Edition
• You may install varying memory sizes in Channel A and Channel B. The
system maps the total size of the lower-sized channel for the dual-channel
configuration. Any excess memory from the higher-sized channel is then
mapped for single-channel operation.
• Always install DIMMs with the same CAS latency. For optimum
compatibility, it is recommended that you obtain memory modules from the
same vendor. Refer to the DDR3 Qualified Vendors List at the ASUS web
site.
• Due to chipset resource allocation, the system may detect less than 8 GB
system memory when you installed four 2 GB DDR3 memory modules.