it looks like it is not compatible with the G1 Gaming, it is compatible with your 1700X.
even though it is not listed as compatible with the G1 Gaming it might be worth a shot to contact EKWB and ask them.
there is a lot of difrent GPU variations on the GTX 1080, so they might have just missed one on their compatible GPU list, you wont know if you dont ask.
yeah just spend another $700 on a GPU so it is compatible with a "Budget" custom loop (i know $292,79 is not realy budget, but in terms of watercooling it is)