PSU upgrade problem

[Andybenham]

I'm gradually upgrading my i7 860 based 8000. Have added a 240gb Samsung SSD, and its running very well. Its now time to upgrade the GT220 GPU, but I thought I'd change the PSU first. I tried to fit a Corsair CX750M, and it fitted in the case, but it didn't seem to work. The PSU fan started up, as did the CPU cooler fan and the case fan, but after around five seconds it all stopped. Around 10 seconds later it tried again, but with the same results. The power button stayed orange. Before you press the power button, the LED on the MOBO is on, saying that it has power but is awaiting the command to start. When I put the old 350watt power supply back, everything was fine. In light of the above I RMA'd the PSU to ebuyer, who promptly provided a replacement, having tried the cx750 and found it faulty. Now it starts to get a bit weird because the replacement cx750m behaved in exactly the same way. Ebuyer have accepted an RMA on this one as well, and offered a third cx750m, but I was starting to get worried at this point, so decided I'd have an all singing all dancing RM650, which conforms to all the very latest standards. The RM650 arrived yesterday, and it behaves exactly the same way as the cx750m. So, has anyone on here actually managed to upgrade the power supply on a XPS 8000 and if so with what, or does anyone one know why the power supplies aren't working. The MOBO is an Intel P55, OX231R, with an i7-860, running windows 7, 64

 

[prorama]

I THING You must change that PSU