A reflow over the gpu (perhaps cpu as well) and hana chip will solve the problem.
You won't have to do an x-clamp replacement with a good reflow.
Once the chips are reflowed, you will need to apply artic silver 5 (AS5) thermal compound paste to both the gpu and cpu chips.
The stock fans 'have to be replaced' with talismoon whisper max fans or mod the case by cutting out vent holes to pull out air with 80mm or 120mm fans. Some people externalize the dvd drive to internalize a pair of 120mm fans.
A 12v power source is needed to run the fans. A molex cable can be soldered beneath the power supply (psu) board points (google for the diagram) if you wan to get power from the 360. You can also use a PC or IDE to usb psu to get a 12v source.
PS1/SCPH-7501 | MM3 modchip
PS2 v9 | 250GB hdd | PS3 component cable | katana 32mb mc
PS3/CECH-2001B | 250GB hdd | 3.65 ofw