Last night my system died on me. The problem is:
When i press the start button... the power LED comes on but there is no POST beep or BIOS screen or boot up. The SMPS fan and Processor fans also dont come on at all. there is a small LED next to the SMPS plug on the motherboard that does light up when the system is connected to a power source.
The config of my sys is
Intel Pentium D 3.0Ghz processor
4 GB DDR2 Ram (1X4)
Nvida 256MB Video card
Part of the system configuration is the kind of PSU you have in your system.
So, what kind of PSU?
Try to borrow a known good PSU. Or better yet, see if you can test your PSU in another working system. If you cannot do that, try to borrow a DMM to measure the voltages. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.
You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead.