This video demonstrates a method of fixing the E 74 Xbox 360 error. In order to do this, you first must disassemble your XBox, which will void your warranty, so this is at your own risk. You remove the X-clamp underneath the large, flat heat sink on the motherboard, and then remove the heat sink itself. Now turn on the XBox, and it should give you 2 red lights. Now turn it back off. If it will not turn off from the power button, pull the power cord out from the back, but plug it back in after it's off. Now clean the thermal grease/tape off the CPU and heat sink, and replace it with a aftermarket high-quality thermal grease. Now put the heat sink back into place, and press it down. Now turn the XBox back on, and the E 74 error should be fixed, and the XBox should start up as normal.