What I do today.
I use a 3 socket plug (like the kind you find on a cpu fan) and wire that to the mod points on the card. This way, if there is an issue with the card or variable resistor (VR), I can just pull it out and the card is back to stock.
I also use a 4 socket molex plug, wired to the read point for the DMM.
I just use the other end of the card to ground the DMM, as a rule I don't add a ground point in the molex plug.
Here you can see a picture of what it looks like.
Before you add a VR, check the reading of your stock volts, here you can see it's 1.20v
Check to make sure the resistance on the VR is set to max
Now that we are happy that it's set to the max resistance, plug it in.
Just doing that raised the voltage to 1.23
Now lower the resistance of the VR (anticlockwise in this case) to raise the voltage to the level you want.
Easy yes
I've almost lost count of what I've modded since I started, but here are some pictures of some cards I've done over the last month or two.
Two 4870's
Two GTX280's
4870X2
