computer wont power up.

[fireboy1]

My name is james and i need help with my computer really bad.
I was working on my dell XPS8700 with a dell 0kwt8 mainboard an i7-4770 3.8 ghz cpu with radeon r9-270 2gb gpu and a corsair cx750 psu. I have tried a brand new psu, a corsair 850 watt modular and still nothing but the power led and mouse comes on. I am afraid the mainboard is the problem.
i was surfing the interweb when it just shut off as if the plug had been pulled. i pushed the power button and nothing but the led on the power button came on. No fans came on, hard drives dont not spin up even the graphics card doesn't come on. the mouse however does come on but the keyboard or the case LEDs do not come on.
Please help!! I have no clue what happened.

 

[Tolik_]

It looks like you PSU died. Do you have another PSU that you can put into your computer

 

[fireboy1]

yeah i have a brand new corsair 850 modular and still get the same results.

 

[Tolik_]

Well in that case it could be your motherbaord. Do you have another motherboard that you can test on

 

[fireboy1]

I apologize for getting back to so late. I am a firefighter for my city and a volunteer forest firefighter. Unfortunately no i don't but i was looking at a new mainboard today. Its a gigabyte GA-z97x gaming 5. I am hoping its a good board and will work with the rest of my components. Haven't purchased it yet due to being somewhat new to installing a mainboard and i don't know all i should to purchase one.
I know my CPU is a LGA 1150 socket but my old bios was A11 haswell i think. Do you have any thoughts on the board listed above?

 

[Tolik_]

Wow that impressive. Thanks for the all the work that you guys do. Well your motherboard should work fine. Let me know how the setup goes. If you have any more questions just email me. I will help you with everything I know