home made risers with "activate 1x" hotplug bridge, and additional power molex
DO NOT DO THAT!You are giving those 12 volts back to the MB if you don't cut the wires!
You should cut the 5 power wires from the flat cable first, than solder additional power.
And if you are wondering here you will see which five lines you need to cut, than solder 12v to them:
http://en.wikipedia.org/wiki/PCI_Express#Pinout
dual old p4 coolers to mach gpu0 and gpu1 temps
This is the stupidest thing I've seen! 
At least put them to the right where the VRMs are. I can't see if you are using thermal paste but if u aren't, put lots of paste cause the surface is not perfect, and put them on the back of the VRMs, hopefully you will see a drop in the Phase Temperatures.
you dont post here if u dont know s**t!
it is ultra-super-good to sent 12v back to mobo, check pictures of burnt 12v pins @ 24pin atx when using many cards.
this is a big issue for miners.
there are even special thingies like this:
check the video:
http://www.youtube.com/watch?v=N9SLjiR7Q4s
to not make your mobo look like that [googled, not mine]:
https://bitcointalk.org/index.php?topic=53904.msg642672#msg642672
also your "stupidest thing" made my temps from 81/72/80/71 to 72/69/71/69 for free [got a lot of theese] and zero work [2 min?]. there is some thermal paste of course.
i have some radiators on the VRM's on other rigs, these two cards have nice vrm temps and are not hot over there
do not teach your father how to make kids, don't try to teach grandma how to suck eggs
i can see your homemade cables are much better :
https://bitcointalk.org/index.php?topic=7216.msg1520593#msg1520593
Check aaaaaaaand mate.