Example

• System BIOS (include mainboard BIOS , add in card BIOS , etc
  
• Mainboard Resources (I/O APIC)
  
• Memory Mapped I/O
  
• PCI / AGP / PCI Express Configuration Space
  
• Additional PCI Device Memory
  
• VGA Memory (Video Aperture Size)
  
• Other chipset and system device .

The different onboard devices or PCI add-in cards on system , It will show different total memory size in Operation System . Example to JETWAY 939GT4- SLI-G mainboard , When you plug in one PCI-Express graphic card , It will occupy 256Mbytes physical system memory , when you make SLI function , Plug in Another one PCI-Express graphic card , it will occupy another 256M bytes physical system memory , so the Operation System will report to remain less 3.0G Bytes system memory (include BIOS / APIC / I/O APIC / VGA memory / LAN device / Audio device .. occupied system memory) Normally , More PCI device installed it will require more memory resources , This limitation appear different platform and chipsets when you work in Windows XP 32-bit edition Operating System . If you install Windows XP 32-bit edition Operating System , we recommend you install less than 3G Bytes system memory . If your system memory over 3G Bytes , you must fit following two condition :
1. The memory controller support memory swap function . e.g. Intel 975X, 955X, Nvidia NF4 SLI Intel Edition, Nvidia NF4 SLI X16 , and AMD K8 CPU platform support ��memory swap function .
2. Windows XP Pro X64 Edition . (64bit edition) or other OS which can address more than 4GB memory. You can refer to Intel web link below information:
http://www.intel.com/support/motherboards/server/sb/cs-016594.htm