How do I fix the Xbox 360 3 rings of death when it happens on two different consoles?

Ok, so I have two Xbox 360 consoles, One is the White Xbox 360 Pro / Xbox 360 Premium, that was sent back to Microsoft Support on warranty because of the 3 rings of death problem,and has been working fine ever since. The other one is the Black Xbox 360 Pro / Xbox 360 Premium which has had no problems so far except for the fact we use an Intercooler fan. Just recently I've had problems with the White console after seeing the warning signs of freeze ups and soon the 3 red lights. I did the "disconnect the AV power supply and reconnect firmly to the console" and and did the whole "plug into to a different outlet and if that doesn't work plugged it in a different outlet in a different room" thing but the light was always orange as it normally was and it still didn't work. So I thought it was a dust problem and used the Perfect Duster can and sprayed all the holes where I saw dust on the console and the AV power supply but I still got the three red rings. So I took the other power supply from the Black Xbox 360, thinking it was a bad AV power supply and plugged that one into the White Console but I still couldn't get it to work. So I sprayed the holes with the duster on that power supply and plugged it back in the Black Xbox. But after I did that the Black Xbox got the 3 red rings so now two Xbox 360 consoles have the problem. I was thinking maybe I screwed them both up from the dust cleaner but the White console already wasn't working before I used the dust cleaner. Now I'm out of ideas and was hoping someone would be able to help me figure out the problem, Please.