Asus X555LD (I3-4030U) ram upgrade to 8gb issues

Hi, I'm not succeeding to get my above (X555LD) laptop a ram upgrade to 8gb since no memory sodimm that I've tried so far didn't work.

The laptop has a soldered 4gb ddr3 1600c11 module and a free sodimm slot.

Tried with two 1333 cl9 modules (previously functioning on an older Vaio) and with a new Kingston KVR16S11S8/4 4GB 1600MHz CL11 module but none of them worked. The windows (8.1 Pro, x64) and the bios either won't see the ram upgrade.

I've also updated the bios from the 310 to the 312, no way.

There only is an Aida64 Extreme 5.0 (installed) able to "recognize" my second ram module (no matter this is a 1333 Hynix or a 1600 Kingston) and the first one (called the system memory) is about 3.7gb instead of 4gb (but this maybe because of some video shared memory).

I really don't know what to do any more, it's not even a ddr3l (low voltage) memory related issue since the cpuz reads a 1.5v, Kingston (soldered) module for the stock one.

Thanks for any hints,

Lionel

Nope, this ram slot or module (like I said I tried with three different sodimm's) doesn't wanna work at al.

There's nothing to be uncheck on msconfig and the resource monitor only shows the main system (default, 4gb) ram:

Here's what I get with the cpuz (showing the same stock memory):

And with the aida64:

http://i.imgur.com/4HCJSwC.jpg

I really don't know what else to try except for (maybe) getting another (new) different 4gb 1600mhz sodimm.