YAY ! fixed it. all i did was took the xbox apart and removed the xclamp. took the heat sink out and removed the bolts from it then i got some 30mm m5 roofing bolts and hack sawed them down to 10 mm. got 8 m5 washers to put either side of the motherboard and re-attached the heatsink using the botls and got rid of microsofts old fixings. all i have to do now is re drill the back metal plate so my bolts fit snug. i didnt even replace the thermal compound on the heatsink i just left the old stuff on then when i put it all back togeva i took the fan from its original place but left it sucking air from the metal thing next to the heat sink. (this is the safest way of overheating the xbox without damage) let it overheat for 10 mins. turned it off let it cool for 10 - 15 mins. and my xbox is workin like a dream
god i love youtube !
if anyone needs any help with any problems with their xbox just drop me a message. i have now fixed the 3 red rings. the open disk tray erro. and the E74 error. all in all microsoft would have now charged me over £200 if they were all fixed seperatley and it has cost me £1.02 for the bolts and washers from screwfix.