Biostar

If user try to insert a PCI-E VGA card + H55 series motherboards + Clarkdale CPU +  4GB Memory module, then Win7 64Bit O.S will only recognize 3.87GB.

This is because Intel define two block area to reserve as EP-UMA (1-64MB) + 0MB-64MB wasted. So system will not be able to recognize full 4GB OS due to chipset limitation.