Just found out that both of my GPUs (Sapphire HD 7970 Dual-X OC Boost and Gigabyte Windforce R9 280X) use a custom PCB. I didn't know there were various versions of the Sapphire 7970, so I assumed I had a supported version. I've already bought the Heatkiller R9 280X waterblock, opened it and applied the thermal pads. Not sure if they're returnable.
At this point I'm considering getting the EK VGA Supreme Waterblock (http://www.frozencpu.com/products/18729/ex-blc-1413/EK_VGA_Supremacy_Universal_High_Performance_VGA_Cooling_Block_-_HWBOT_Edition_EK-VGA_Supremacy_HWBOT_Edition.html). If I do, do I need to buy another universal waterblock? Does this "Supreme Waterblock" only work with EK products? I'm hoping they'll work with my Heatkiller waterblocks.
If it's installed just by itself, can it handle 1/2 ID and 3/4 OD tubing?