The 360 used an ATI Chip, and ATI Chips from that era were known to have a Solder-Joint and Substrate issue, which also manifested into the XBOX360, the PlayStation3 on the otherhand never had any issues regarding Graphics Chips, the 7800s were pretty efficient in theyre own way,one problem they have,but its not really a concern, its the Substrate failure, like any other Graphics Chip,if its tortured to 80ºCs+, which is bound to show artifacts or even give the GLOD,which only a RSX replacement will fix it.
Remind that Microsoft only fixed this issue in the 65nm era, with the Jasper boards "i think", the original Xenons where prone to failure from day one, not to mention they rushed the console without any proper testing, they took a big hit in the process,but at least they managed, although a Sony loyal consumer, the XBOX 360 its a great console to won, it had its flaws such as the PC Style Disc drive,and the external power brick,not to menton HDD Encryption,but beyond that its a great console to won, had a S Model,but gave it to a friend, now i am searching for a Red "Resident Evil 5" Jasper 360,just because it looks good, not to mention Forza,still haven´t played thoes, but the Xbox One, oh dear,not touching that