Hi, I just bought an HP pavilion e9300 a few week ago. And I am going to upgrade the power supply so that I can get a new graphic card--ATI 4870 which requires at least 500 watt power supply. My current computer is shipped with a 350 watt power supply. I will probably get a 650 watt considering the 70% effeciency of power supply. However, when I talked to an HP technician, he insisted that I could go for a power supply with no more 450 watt. Because the system I just got has a motherboard which has a max power limit 450 watt. He said if I go beyond that, the motherboard will burn out. So what shall I do? I really want to get ATI 4870 work well on my computer. Thx very much.