I have the Apple 50mhz card in my homemade Q700 and had a real problem with overheating. The 601 would get hot and the system would stop recognizing it. It would lock up and on reboot would boot the 040. I solved that by cutting a small square of tin and putting it between the CPU and the heatsink but no thermal compound. The heat sink was a little loose and the tin square tightened the gap right up and a lot more heat is drawn away than before. I then added a fan from a clock chipping kit for good measure and since then no more problems.