How can I confirm that its the MB not the CPU thats dead?

deadfish

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Aug 5, 2009
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Background story: I purchased a Corsair 600T case, transferred all my hardware to the new case. A XFX780i motherboard, Intel Duo Core 3.06 E7600.
I triple checked all my connections before firing it. Came to life, all was good for about 4 days.

The case has a front panel for headphones and microphone and a fan controller.

I decided I need to do a skype phone call.. and why not use the front panel.
The moment I plugged the microphone in (a non powered, old school POS microphone)... lights out computer dead.

I have tried everything to get up and running. Went and bought a new PSU... I was thinking that maybe the 5v or 3v rail got knocked out by ESD.
Get a new PSU... plug it in... triple check... NOTHING. Checked the wall unit too, etc.

ALL I get is a blue LED light up on the MB and nothing past that.

Since this happened I have: uninstalled and reinstalled all hardware, cleared the CMOS via the jumper, reset the CPU and fan in place, the battery, memory, GPU... Nothing.
All I get is this blue led... no fans spin up ever.

So is it the CPU or the MB? Or Both?
Thanks in advance.