X58 is too old and is likely limited to 5-6 GPUs.
H97 should work though. Does it even boot with more than 6 GPUs? If it does, your OS is likely the issue.
You might be able to get 5-6 cards with the small boards, but YMMV. The chipset doesn't really matter I think, the multiplier combines the signal of all 4 cards into 1 lane.
H97 or any other lga1150 socket board wont work. For more than like 7 GPUs.
I have 2 boards of this era, one is an Asrock H97 Anniversary, the other is a Gigabyte B85M board. Both of them will only work up to a max of 7 GPUs. If 8 GPUs are plugged in in any configuration, the board wont even POST.
You need a newer board that supports the Above 4G decoding setting. These old boards wont do it.
I have 8 running fine on a Z270 board, and Im sure I can do more if I wanted.