Not sure where you're getting the info that the 6700K won't recognize RAM at 3000MHz, my 6600K rig with DDR4 RAM is 3000Mhz and the RAM speed is recognized just fine in the BIOS. It might not do the full 3200MHz (cause damn that is HIGH!) but it will hit 3000Mhz if your BIOS is up to date etc.
First I'm hearing of Dolphin running much better with nVidia cards. Shame, as I've ordered a 380X, but nVidia's anti-competitive practices at the moment turn me off them. For regular PC gaming AMD seem to be making serious strides in DX12 anyway. Maybe that will be true too with Dolphin's DX12? I would make sure of that before you buy.
Also, I would go with air cooling. I had a h80i for my last cpu and a watercooler 770 too and the rig was loud. Now I have a noctua air cooler and its keeps my components at about 24c while also being so so quiet.
First I'm hearing of Dolphin running much better with nVidia cards. Shame, as I've ordered a 380X, but nVidia's anti-competitive practices at the moment turn me off them. For regular PC gaming AMD seem to be making serious strides in DX12 anyway. Maybe that will be true too with Dolphin's DX12? I would make sure of that before you buy.
Also, I would go with air cooling. I had a h80i for my last cpu and a watercooler 770 too and the rig was loud. Now I have a noctua air cooler and its keeps my components at about 24c while also being so so quiet.