I did a variation of this fix. My Xbox froze for the first time on a Tues. Still 3RL'd and back to working with a couple of resets on Wed. Couldn't shake off the 3RL on Thursday anymore so I decided to crack it open for the first time, noticed the mem underneed had pressure pads. (too thick to be thermal pads), so I reinforced it with a strip of carboard (1-2mm thick), 1 for each pair of mem chips. Reassembled everything, and 3RL's never came back. Stressed it quite a bit over the weekend, and it still works.
(I noticed how the front of the mobo would be flexing a bit down when I screwed it back to the metal case, so I guess that solved it.) So that's 5 days straight it has worked and booted up fine. (even got a electrical power trip, and a temporary 3RL, but a reset fixed that)
I will still observe this one.