Dell Inspiron 530 - Plug it in, immediately powers up, PS fan and Video card fan start, power button shows amber light and does not turn off power, motherboard shows amber light instead of green; doesn't matter whether video and keyboard are connected. Changed video card, removed NIC, removed all RAM except Bank 0 slot 0 and reseated that; nothing has affected the symptoms indicated.

Hi

This seems like a power management problem on the motherboard.

Disconnect the power cable. Remove the small silver CMOS battery for 2 minutes to clear the BIOS Memory. Reinstall the battery and reconnect the power.

Look carefully at the power lines coming from the Power Supply Unit (PSU) and make sure that no one power channel is powering an unequal load of devices. Try and divide the load as evenly as possible amonst the power lines.

If none of this solves the problem, then consider upgrading the fitted 300W PSU to one with a higher Wattage, as 300W is on the low side for current standards. 450W-500W is more typical nowadays. The higher the Wattage you can afford (up to a 650W maximum for this particular specification of PC) the better

A higher wattage PSU will work well within its capacity and therefore under less strain than the current one. The symptoms you describe could be signs of the current PSU straining at the limits of its performance range to power all the devices inside as well as maintaining the computer's heavy workload of interaction with all the devices connected to it.

I hope this helps.