HP has the G1 and G2 versions of the Z Turbo Drive but those are for HP workstations later than the Z400/Z600/Z800. What about us with those or even us using the still excellent xw6400/8400/6600/8600/4600 generation of workstations?
I am now running the Kingston Predator M.2 PCIe 240GB card as my boot drive in one of my W7Pro64 Z600 workstations, and it is running great. I also did some testing and got that up and running in one of my xw6400 and xw6600 workstations. Have not yet tried it on a spare xw4600 but have no reason to believe it will not work in that too. The Z800 works this way just like the Z600.
I'll post more details when I get more time. HP has two storage controller drivers listed for the ZX00 series and the more recent one (11.5.4.1001) did not work when I updated to that, so stick with the original (9.6.0.1014). The build blue screened the instant boot went beyond BIOS when I used that later driver. Also, my Acronis clone software would not clone over my installed SSD build correctly until I changed the Acronis mage capture type to sector by sector. I used the built in Windows DiskPart to clear the Predator before doing the clone. I used MBR partition type and NTFS long type formatting before the clone. I removed all other drives from the Z600 before the clone process onto the Predator, and had an external eSATA-attached drive as my image source for this. My initial attempts had failed with blue screens, but my breakthrough by doing a clean install from a W7Pro64SP1 system builder DVD, from scratch, so I knew then that it would work. Then I worked my way back to successful cloning of my original SSD's install onto the Predator using Acronis and the several tricks mentioned above. The Predator now shows up in BIOS as a bootable device and I can change boot devices in BIOS the normal way without issue, and have the Predator set as the primary boot device generally.
It is very fast, and stable. For those who pay attention to such things: This upgrade is not like we experienced going from HDD to SSD. The feel is more like an upgrade from a moderate to a very fast video card. Noticable jump in speed, for sure, and well worth it.
You want to place that in a PCIe slot that is generation 2 or higher, and has at least x4 lanes. For my particular Z600 (my main home office workstation) I have a HP "2x2" Texas Instruments chipset USB3 card up in the top PCIe slot that would work for this, so I put the Predator card down in the lower PCIe x16 slot you'd normally think of as for a second video card. For those with xw6400 workstations there are zero PCIe Gen 2 slots so you'll run at 1/2 speed. For the xw6600 and xw4600 the two PCIe x16 slots are Gen 2 so use the lower of those for this card. You can look up the PCIe slot type posiitons of your ZX00 workstations in the technical and service manual. The Predator is a PCIe Gen 2 card that can run through 4 PCIe lanes so you want to at least give it that. When you see "PCIe2 x16 (x8 electrical)" in a manual that means it is a PCIe generation 2 slot (higher speed) and though it is x16 morphology for the slot it only has 8 PCIe lanes available for use. It is fine to put this card in a slot that has higher capabilities than the card itself, but you'll get no added speed benefit from that. The notation is still evolving and HP has older notations in the old manuals. None of these workstations have PCIe generation 3 slots.
The ZX00 series are SATA generation II workstations, and this is one way to break through the speed limits of that. I'm using the Predator as my boot/applications drive, and just put in a nice enterprise grade 500 GB Samsung SSD as my "documents" drive. That combo is very fast.
The HP Z Turbo M.2 cards are two types: the G1 has an AHCI type of controller and the G2 has a NVMe type. The G2 is officially only supposed to work in the ZX40 generation of workstations. You might have a shot at getting the G1 to work on the ZX00 series workstations but I don't think anyone will ever get the G2 to work in those because of the chipset and BIOS limitations of the ZX00 series. One of our very creative forum members did figure out a workaround to get a G2 to work in his ZX20 workstation (I think it was a Z420), which is not supposed to be possible. That is an example of something that worked but is surely not "supported" by HP. The ZX20 and ZX40 generations, however, have a lot in common but there is a big gulf between those and the ZX00 generation. For the G2 in ZX20 workaround see towards the bottom of this page HERE.
The Predator M.2 PCIe card has an AHCI type of controller, and is proven to work so I'm advising my need-for-speed friends to go for that now in their ZX00 and xw6600/xw8600 and xw4600 HP workstations.