I've got a Dell XPS 600 on the bench. The PC will not boot, even from a CD. When I turn the power on, the power switch shows yellow and the monitor also has the yellow power button. I don't even get to the BIOS. All the fans run when I start the PC. I've replaced the video card but it still doesn't work. I've replaced the hard drive, but no joy. This model has the power supply attached under the case with dual fans. I don't even have a power supply tester for this model. It has a 24 pin connector to the motherboard. I priced new power supplies for this model and they run around $90.00 plus shipping for a refurb. Is there a way I can test the power supply to see if it is defective? Do they make a tester for this kind of connection?