GA-x58a-ud7 Mobo dead, pls help !

[snofte]

My good old x58a-ud7 suddenly wont start.  Blue power button on mobo lights up, pressing it and two leds on mobo lights up, one green. one yellow.
These two are just below 3 other leds from the top of the led-row.  Nothing else happens, no fans, no nothing.
Power supply problem ?
Cpu burned ?
Mobo burned ?
Any help highly appreciated.

regards
snofte

[snofte]

Changed the psu, still no luck.  One led lits on the mobo, nothing else happens.
Best guess for next step:
Replace cpu or mobo ?
Any hint for next step highly appreciated. 

[absic]

Have you checked that mouse keyboard are OK?

Remove all attached USB devices and see if that helps.

Have you tried clearing CMOS?

Can you check the RAM modules by swapping them about and trying just one stick to see if PC will POST/BOOT?

What hardware are you actually using?

[snofte]

Thanks for reply.
Mouse/keyboard ok on other pc
Removed all usb`s
Cleared cmos via button on mobo next to internal powerbutton on the mobo
Switched ram-modules.
Checked the original psu, by trying to offline jump-start it via shorting green and black wire
with paperclip. Attached a small fan for load.
Psu did NOT start the fan !!! 
Tried exactly same procedure on new psu, and fan starts spinning ok !
Sp I guess original psu is faulty, and has maybe also damaged mobo or cpu.
Original psu is Seasonic x650 watts
To the mobo is installed i7 990x cpu and several hdds.
2 sticks of ram, each 8 gb kingston.
Big question now is :  Which unit should I start to replace first ?  cpu og mobo ?
(guess replacing cpu firs tis the most easy path, but maybe buying new cpu is a waste of money
if the mobo is the culprit ?)
Any advise highly appreciated. 
 

[absic]

To be honest it is very rare for CPU to fail and I would look at replacing the motherboard as PSU failure often damages this, rather than other parts.

[snofte]

Thanks for advise.  Replacement mobo found and bought on ebay us.
Relieved that I could find this similiar mobo, I have 3 hdds with lots of installed programs,
one xp, one w7, one w8.1.  Just the thought of starting reinstalling all this on another
brand of mobo is scaring to say the least.  Now I can at least keep all 3 hdds as they are.