Try with one stick only in the third slot.
Is it possible to manually enter your RAM specs/timings in the BIOS?
If you can, I would. (There should timings on stickers on the RAM modules.)
But as it stands, it sounds like the motherboard may possibly on it's way it out (if it's old) or a dud (if it's new).
Quote: Originally Posted by quartaela
i have just tried windows memory diagnostics tools as an advice of Technical service and as a result no error found.
I wouldn't put to much faith in the Windows Tool tbh.