I need upgrade my ram modules.and there is lot of options.Like Kingston DDR2 HyperX PC6400 memory.so i just ask any suggestion for new ram(8gb total)???
should i use kingston hyperx memory???
my pc is:
Motherboard:Gigabyte EP45-UD3LR-bios version is:F11
Revision v1.0
Ram 4gb pc 6400-800mhz
ati hd 4670 512mb
onboard soundcard
samsung 500gb spinpoint hdd
500w psu
pioneer dvd writer

OS:windows 7 home premium 64bit
ps that online sca doesnt work

I would try to match your existing RAM just to ensure the best chance of compatibility.

i think you are right.. but example:
Kingston DDR2 HyperX PC8500 2GB CL5 is cheaper than pc6400 800mhz memory.