I have an old computer that I want to put back in order for my son. It has a MSI 850E mainboard with two 128mb kingston kvr800a 16-4/128 memory sticks. I wanted to upgrade it to 512mb. As far as I can tell, these may be PC800 40ns, but I'm not sure. I have 2 samsung MR18R0828AN1-CK8 modules (PC800 45ns) I also have some PC700 45ns ,PC711 45ns and PC600 53ns. Will the machine work properly with 2 PC800 modules @ 40ns and 2 PC800 modules @ 45ns? Can I mix PC 800, 711, 700, and 600? What problems will occur?