I got a xbox 360 core system from ebay yesturday, and it was geting the 3 red lights (just as the auction said).
Error code : 0102 (did it a few times to make sure at different boots)
It seams asif i fixed it (geting artic silver 5 in the mail in around 3 days from now

).
Here is my story, i took the system down to nothing (includeing takeing heat sinks off), and also i did press down on many of the RAM chips (mainly checking heat and connection, might of been loose not 100% sure)
The first 2 or 3 times i turned it on i got the 0102 error (possible its also got overheating in the unknown part).
after that i got it to boot once, so i rebooted it a few times, every time worked, so i left it on for around 1-1.5 hours and then looked down (was playing counter strike lol) and 3 red lights but fully working in the dash(error 0102 agian). I didnt have a game so i turned it back off and left it.
Today i got a game (Full Auto) and loaded it on my projector (hd and all with VGA input) and used my vga cables and played the game for around 10-15 mins b4 the same error.
Then i figured it must be heat is causeing it so i put a very powerfull fan on it (blowing in the side holes while laying down) and never got the error in 2 hours of solid play. Then i turned off it, and the fan, waited around an hour and turned it back on, same thing 10-15 min of play and that error (never got 2 lights only the 3, 0102).
When i get the Artic Silver 5 in the mail i will install it and tell every one how my luck goes

.
Thanks for the great info (if not for you guys, i would never of touched the RAM chips lol)
Cmd19872002