Alienware 15 r2 error 4 beeps code.ram issue

[armands0212@gmail.com]

Hi all.i have problem with my alienware 15 r2.basically its keep beeping 4 times at startup-what means there is ram issue.i already tried 10 different ram sticks with different speeds and voltages but nothing helps.tried to flash bios to see if that will help-but no luck.
Ram sockets looks fine as well,cleaned them and carefully inspected

So maybe someone had this problem as well with any of dell laptops and have some ideas what else i can do?

Thanks