I have a Z440 that came with a Z Turbo card pre-installed as a boot drive. I use the Z turbo only for my OS and installed applications.
I edit video so i bought the Intel 750 NVMe 1.2 TB PCIe SSD card in june 2015 and use it as a scratch disk. It has worked without flaws and i can really recommend it. The price has really dropped so it´s relatively cheap right now. The Intel 750 NVMe can be used with Windows 7 and so can the HP Z Turbo cards.
Intel 750 NVMe 1.2 TB PCIe review:
http://www.guru3d.com/articles-pages/intel-750-nvme-1-2-tb-pcie-ssd-review,1.html