This workmanship is really excellent, great job :up:
There are a few things that I think need to be addressed. For one I think you need to re-do your GPU arrangement.
http://img150.imageshack.us/img150/7157/dsc5995copy.jpg
1) That fill line will trap air, which in itself is not a problem but you need to constantly monitor your coolant level to make sure the 2nd GPU block doesn't basically become another res (i.e. trap more and more air).
2) Remove 1 of these d-plugs and plug it up. I don't think you intend to go parallel here.
3) I assume this is the inlet? The way it's setup now, your coolant will shoot up, thru the d-plug, past the other block, and into the fill line. It will splash and foam and mix with air and drag small bubbles into your loop. No good.
My suggestions for now:
Move the inlet to the other port. Remove the d-plug direct above that. Maybe put a valve on that fill line.
Additionally, having 90deg turns right after the pump will hurt your flow.
