PCI-E drives (also known as Revo-Drives or Z-Drives) are manufactured by OCZ (which is currently the only PCI-E drives manufacturer and their advantage is obvious:
They don't use any of the classic data transfer protocols, they take up a PCI-E slot on the computer's motherboard, and - of course - they use speeds which in many cases are up to 5 (!) times faster than that of SSDs.

In particular, these drives read data with a speed that can reach 1500 Μbps and write with speeds of 1400 Mbps, which are much faster than all other conventional drives (SATA or SSD). At the same time, they have all the advantages of SSDs (no mechanical parts etc) but also their disadvantages (NAND chips with encryption, limited number of re-writable cycles etc).

As far as data recovery is concerned, the problem is that these drives use a Sandforce Controller, which uses a 128bit AES. encryption. This means that, for the time being, these drives are non-recoverable.

The good news is, though, that Sandforce introduced a new technology, known as RAISE (Redundant Array of Independant Silicon Elements) which is something similar to hard drives' RAID arrays and it uses a parity just like RAID 5. This means that if one of the chips gets damaged, the drive will keep operating, even downgraded.

But if the damage is bigger...

Northwind's experienced technicians are investigating these drives to find a way to decrypt them in order to succeed in recovering data.

We have to stress the fact that these drives' distinctiveness is in the controller that OCZ uses. If, in the future, more manufacturers produce drives like that using other controllers the decryption could be easy or not needed at all.