Computer won't power on. Motherboard LED's

[TwistyNado]

I have this old HP ProDesk 405 G2 MT, and when recently trying to boot up, shows no sign of life at all. I've reset the CMOS battery, swapped PSU's, and changed RAM. The power button doesn't do anything and the PSU light and Motherboard light are both enabled (Motherboard AUX Power). Does anyone have any idea on how I can troubleshoot this further and/or fix this issue? Thanks.

[WAWood]

So you have an LED on both the PSU and mobo -- and they are both Lit? or not?

[TwistyNado]

Yes, both LED's are lit.

[WAWood]

OK, if both LEDs are lit, unfortunately, all that means is the PSU is running and the motherboard is getting power.

There should also be some fan noise -- loud at first and then quieting down after a few seconds.  IF so, that means Windows is trying to boot -- and you should then be getting boot error messages, or disk error messages on the screen.

If are not getting fan nose, then look so see if the case fan is actually running.  IF it is not, while the fan could have died, more likely, this indicates the motherboard has fail because the fan power leads plug directly into the motherboard.

[TwistyNado · Accepted solution]

The motherboard is dead. That was the jssue