Ops my bad, it was fairly long post.....don`t know what happened... So lets try again. You can create Vm without deleting old one, so that you can be sure if the problem is with the xml itself. It is 30 second process like 3-4 clicks. It is recommended to use OVMF for passthru, most ppl had better success with it .( for me works both ways). As for your hardware OVMF and Seabios are emulations and are not dependent on what type bios you use in your real machine. Interestingly most ppl recommend to boot unraid legacy and use ovmf for vms. (for me works both) One of the problem for you which may arise is that does you have uefi bios on the 1030. But it is not so big, because you wouldn't see VM boot process but you will see output on your monitor when windows starts and have installed drivers. As for that, that your windows is installed on seabios, yes it wont start as it is on OVMF. Microsoft had tool for converting "mbr" to "gpt" and i thing there was a command to do it from command prompt. For the license thing it is not a problem you have to just copy 'UUID' number of the old xml > 3th row. And for starters just make another vm template with same version of q35 same vdisk, qlx as 1st gpu and 1030 as second gpu.Start it connect tru vnc and install drivers. And if you afraid that you could mess your vdisk just make a copy of it.... - It will work every update i change chipset version with the new q35 and VM doesn't work and i just recreate it from gui make my edits for uuid and mac address (and multifinctional) and is up. (1 minute).
PS: for the DELL h310 i have one and i had the booting hang problem, it is from that, that controller doesn't have uefi rom so if you try to boot with uefi and have boot option rom enabled in bios it hangs.... So use legacy or disable boot option rom in bios. no taping required.
PS2: For others if something doesn't work don`t try multiple things at the same time, do it one at time methodical. - it will be faster.
#Attach graphics card without turn off?? - Where do you reed this ?
Upload xml and diagnostics and tell my the exact model of the card. Bios looks legeit when open it with hex editor maybe is only legacy or uefi. Maybe that is why it doesn`t start if it is only legacy.
Btw from what i remember with one gpu that has only legacy bios it is not showing windows boot process (tinycore)(because OVMF is uefi emulation) but when windows boot it was ok and showing desktop (just not the part before desktop), but if you don`t have nvidia drivers in windows installed it wont show when booted and only black screen. Did you try with vnc virtual card and 970 as a second card ?
PS: Are you seeing tinycore logo on UBUNTU VM when booting or first thing after start is desktop of ubuntu ?
ilarion's post in GPU passthrough is driving me NUTS. was marked as the answer