mPCIe doesn't mean it will take a mSata. They have the same pins, but different pinouts, hence it, and probably no other drive will work. You need a laptop with an actual mSata slot.
"Mini-SATA, which is distinct from the micro connector, was announced by the Serial ATA International Organization on September 21, 2009. Applications include netbooks and other devices that require a smaller solid-state drive. The connector is similar in appearance to a PCI Express Mini Card interface, and is electrically compatible; however, the data signals (TX±/RX± SATA, PETn0 PETp0 PERn0 PERp0 PCI Express) need connection to the SATA host controller instead of the PCI Express host controlle"
I have been experiencing this exact same problem for the past several days and have been trying to configure a brand new 32GB Samsung mSATA in my HP DV8. It is driving me insane! I had W8.1 preview installed, so I thought it may be a compatability issue with there not being appropriate drivers available to recognize the slot. I removed my other internal hard drive, after attempting to do a fresh install of W7 and it, once again, failing to recognize the mSATA drive.
I decided to mess around with the BIOS to see if there was a way to change the boot order for the internal hard drives, but there is NO option to accomplish that for this mother board. You can switch the typical order of the boot sequence, but not distinguish between the internal drives themselves. Keep in mind this is an 18 inch HP Pavillion series laptop that already has (2) 2.5" HD bays inside it, so this additional slot was open on the motherboard and appeared to be a great option to add a mSATA ssd. This mSATA Samsung SSD just came out of a brand new HP Ultrabook, so I know it is operational and has maybe 2 hours of use on it.I have looked all over to try and confirm what that slot on the board is meant for, since you mentioned the slot can share the same pins, yet not be compatible with an mSATA. That would be hard for me to believe, since this was distributed well after 2009 and is a high end HP laptop with an i7 in it. I just don't understand what I need to do to get the BIOS to recognize this drive, so I can install W7 or W8 on it? PLEASE HELP!
Thanks so much for your time and consideration. AdamUpchurch@Live.com