The HP EliteBook 820 G3 manual states that either a hard drive or a SSD might be installed (page 36). And not both at the same time. Thus, as-is, one can't install two SSD modules in that machine.
The reason: apparently, the SSD connector is right there where the (SSD) SATA disk drive would be placed.
I guess, if one really wants to install a 2nd SSD (in addition to the SSD that occupies the mSATA slot, cf. page 39) one could try following options:
- install a very slim SSD with SATA connector
- install a SSD into the WWAN slot (possibly also needs to be slim)
For both options, I need hardware recommendations.
And perhaps some details, e.g. how the WWAN slot is actually called (mini PCIe?), what modules are compatible (mSata?) and how slim a module would have to be.
Preferably, the SSD module should come from Intel or be of comparable quality.
Here is a combination of the drawings from page 36 and 39 of the manual showing the same drive bay for better visualization of the problem: