Upgrade 2 soldered RAM slot up to 4 solder RAM slot (W7 64bit, Elitebook 8540p)

[CNC--VelMart]

Please help. Very important..
It contains 2 soldered RAM slots, one is accessible at the bottom of the machine, the other is under the keyboard, but there is room for 1-1 non-soldered memory slot on both sides.
Currently I7 640 M Processor and 2x4 GB RAM.
I would replace the processor with an I7 840 QM, and then the machine could handle 16 GB, in principle. By replacing the missing memory sockets (soldering) and connecting two more 4GB RAMs to the new sockets, will the management of the new RAMs work? Unfortunately, there is no money for a machine that has the right features, such as longevity, and 16GB would be handled at least, and the I7 is also important. So that the current one is already an inhabited system. Many tasks are set. But Windows shouldn't be newer than what it is currently either. However, the other machines are already running newer windows, and this is a problem, the newer system. There has been no BIOS update yet, it is in the factory state. Because so far everything is working. On the other hand, you have to leave the built-in Bluetooth with the horribly weak signal, it didn't even work, only for a very short time and failed, so it was taken out. And what should work on Bluetooth was solved with a USB adapter.
The idea of ​​Displayport for notebooks was a very bad idea. I would prefer HDMI, because now it is also a big problem that the image output is not HDMI but Displayport. (You have to operate a display that I couldn't quite create a proper picture with the raspberry pi, but it was successful from another computer via HDMI... of course they ran windows... not that industrial waste raspbian... Another problem is the 3 buttons under the Touch tab, because the rubber stretches and the buttons become unusable. This is a flawed design idea, using rubber for any common human touch surface. or the button press rubber. Whatever the designer's dream was. Failed, useful task supply.)
Will the expansion work with the new RAMs and the machine as 16GB RAM, or what additional changes are needed to make the machine work as 16GB RAM and I7? Yes, I know that instead of a 90W power supply, a 120W one will be needed.