PCI Express SSDs are M.2 and won't work.  There are mSATA drives that may or may not work, but bear  in mind that even if the system does recognize the drive, it will be useable only as a storage drive -- it cannot be used as the boot drive. Note that mini-PCIe/mSATA is not M.2 SATA -- M.2 is a newer form factor that is not compatible with this model system.  
Hello!I would like to know more information about the Mini-PCI Express slot in the Dell Inspirion 3737. I am planning to install a mini pci express ssd instead of the DW1705 module installed in it.Is this possible?
Mini-PCI Express slot in the Dell Inspirion 3737