Yes. It's possible.
You will need to perform all this on a working computer. In my case NVME slot one was my primary windows 10 install. I designate the second NVME slot for a windows 7 install. If you use slot 2 for the NVME, the small PCIe slot will be disabled, so use PCIe slot 4 for any USB expansion card.
You will need a few things.
1. Perhaps a PCIe USB controller. Windows 7 currently does not have and will not support the EVGA dark USB device (intel spec. ASMEDIA seems to work). The USB plug next to the audio ports supported my USB dongle for mouse and keyboard and may be ASMEDIA. Try that before buying a card. If you need a PCIe card then this one works. I happened to have one I used out of another older build. https://www.amazon.com/gp/product/B01MQ5R7I1/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
Initially, I used this card but after removing it and trying various USB ports, the red one next to the audio ports worked.
2. windows 7 burned to dvd for install. The procedure for this is to download a program that will involve installing NVME drivers into the windows 7 installation ISO. Go here and make an account to get the program to do this. https://forums.mydigitallife.net/threads/windows-7-image-updater-skylake-kabylake-coffelake-ryzen-threadripper.76335/
I tried ASUS, GIgabyte and Rufus injector programs. These did not work to recognize the NVME drive.
It is called windows 7 image updater.
Download a windows 7 ISO installation File off of the internet you can find links here https://www.howtogeek.com/186775/how-to-download-windows-7-8-and-8.1-installation-media-legally/
and go to the microsoft website and use your product key to download a copy.
Run the windows 7 image updater and select the windows 7 ISO you downloaded from microsoft. Toggle the options you wish to install and hit start. This could take a few hours (my ISO had all 4 copies of windows 7) and it will show your progress through the process. This will inject the NVME, USB (although onboard USB will not be supported) and current windows updates though 2018 into the final windows 7 installer ISO. This saves so much time as most of the windows updates will already be there.
Once it has finished, burn the windows7.iso to a blank DVD (might use a DL DVDr if you exceed the size of a single layer) Once the windows 7 iso is burned to dvd, shut down, return to bios and put your CD rom as primary boot device. Also toggle windows installation in the bios. This gave me USB wireless keyboard support during the windows 7 installation and booting into the OS (I guess the bios gives you a driver). I did not have mouse support. You can also plug your USB wireless dongle into the PCIe card you bought and installed. It worked for me and I had full mouse and keyboard support. Evidently no driver was needed for my install.
Install the OS. Perform all most current windows updates. You can install the EVGA dark chipset and sound drivers while in windows 7 off of the USB card that came with your motherboard. just allow or force the drivers when it asks. All other drivers except sound and chipset seem to have only windows 10 support but you can try each manual install on the USB card that came with your MB. When you are into your OS, look at the device manager. onboard USB will not be unavailable and one of the network capabilities also will not. I did have ethernet and internet support after boot up into the fresh install. I believe the I219-V was unavailable.
I have full functionality with USB with the PCIe adapter. I wanted a second NVME drive on the board with windows 7 in order to run some programs that are not compatible with windows 10. I can see that some will want to benchmark with windows 7. I'm not opening a debate on why run windows 7 and an EVGA dark. Its your own business why you choose to do so.
This is the easiest way to get windows 7 to work with the Z390 chipset.
If you want to boot into windows 7 NVME from time to time, you can assign your boot drive in the bios to do so. I plan on using the onboard PCIe toggle switch to disable PCIe slot 4 when not in windows 7 to free up resources.
I have the windows 7 ISO with all versions of windows 7 with all the injected NVME drivers and windows 7 updates available. If someone wants to host it and provide a link, send me a PM. It's 4.7 gb and I can upload it. Saves people time. I just don't have hosting for something that large. there's a blue ribbon in it for you.
one caveot. If you go back into a windows 10 NVME, occupying PCI4 will kick you out of sli if you have video cards in slots one and two and the NVIDIA control panel dissappears. Disabling the PCI4 via the onboard toggle switch didn't help. I had to remove the external PCI USB card to get SLI back. Evidently, even though you disable the PCI slot 4 (switch 3), the MB still see a card there and interupts SLI. But hey, not perfect. I'll only use the windows 7 NVME for a limited number of things.
post edited by Delirious - 2019/01/26 13:01:31