Gunna need some serious radiator for that mother. Probably what the card needs for best performance, though, hook it up with a 480 mm rad and watch the temps drop.

240mm would probably give some improvement since the stock only comes with a 120mm and heatsick for the rest of the board 360mm+ is probably recomended.

Now i'm not using Watercooling, nor am an expert at it. But should't the In/Out be in the middle of the Block? The second GPU is quite far away. Wouldn't it lose flow pressure?

Now i'm not using Watercooling, nor am an expert at it. But should't the In/Out be in the middle of the Block? The second GPU is quite far away. Wouldn't it lose flow pressure?

Not much, no. Almost the same pressure, since it's the same flow in series. If it were in the middle, it would be so that water flows in parallel, which reduces pressure (arguably more important than flow rate), raising temperatures (but not by much at all).