Hello Graham,
ASUS ROG Crosshair VII DARK Hero or ASUS ROG Crosshair VIII DARK Hero?
If the motherboard is ASUS ROG Crosshair VIII DARK Hero, the BP-MBASX570CVIIIH water block is compatible. Please check the following link. When you log in, you can purchase, thank you.
https://shop.bitspower.com/index.php?route=product/product&path=67_97_359&product_id=7365