I can confirm my adapter works. I tried it on my Stargate board, and it booted to garbage. But it didn't blow up.
Then I moved it to my Defender. I'd bought a lot of 4164 RAM off a guy I found on a Google search. It's the same 4164 I put in the Stargate board. I pried all the 4116 out and replaced it with the 4164.
It came up! But with a RAM error. I double checked to see if I screwed up inserting any, and sure enough I found one with a leg bent underneath. Replaced that with one of the spares I bought (lucky I got extras!) and it came up again, again with a RAM error. This time I was able to pinpoint which one with the onboard RAM test. Replaced that with another spare. This time it booted to garbage. Replaced it with yet ANOTHER spare, and it came up and passed all RAM tests! Yay, I have my Defender back!
This also gives me hope that one or two of the 4164 that I put on the Stargate board are bad since it also booted to garbage. Unfortunately it's impossible to determine which one.