Unexpected shutdown and hibernation (MBP 13 Early 2011)

Hello,

I'm getting a issue with my MacBook Pro :

1. When my Mac is on standby too long, it goes in what I call "hibernation" mode, meaning by this the mode in which you go when your Mac laptop fully runs out of battery.
2. My MBP often shutdown when moving it too suddenly.

I tweaked my Mac by replacing the HDD by a SSD and replacing the Superdrive by the HDD. I also changed my 4Gb of 1033 MHz RAM with 16Gb of 1600 MHz RAM.

When the problem started a few weeks ago, I decided to make a clean install of Mac OS. Today, I removed the HDD and replaced it by the Superdrive. The only tweak remaining on my computer is now the 16Gb of RAM.

I already tried PRAM, NVRAM and SMC reset. I have deactivated the SMS (Sudden Motion Sensor).

The problem appears to me to be physical and I am actually thinking about a bad contact. But I hope you'll be able to give me other answers or to deal with mine in depth.

Have a nice day.